Attributes (or, in 5th edition, abilities) describe the inborn physical, mental and social faculties of a character. Most roleplaying systems try to keep traits as simple as possible. The attributes in D&D have been the same for decades and are used in other games, as well. They are: Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma.
Attributes are ranked numerically to show how much of a trait a character has, or how well they perform in that area. For example: the average toad has a Strength of 1 because toads are not that strong, but the same toad will have a Dexterity of 12 because of how quickly it can move. A poor rating in a trait is accompanied by a penalty, because the character has trouble with that attribute. A rating of 1 has a -5 penalty. Our toad will have to subtract five from every Strength roll it makes.
An average rating carries no penalty and no bonus, like the toad's Constitution of 11. The toad's Dexterity of 12 is high enough, however, to give him a +1 bonus (called an ability modifier) on all rolls that involve Dexterity (more on this later). Different races may have bonuses or penalties to certain attributes, which a player should keep in mind during character creation. There are different ways to raise your attributes later in the game, however, such as by having your character wear magic items that offer a boost to a specific score. So if you start with a score that is lower than you'd like, look for chances to improve it.
Strength, Dexterity and Constitution are all vital for characters that involved in a lot of hand-to-hand combat. You have to be able to dish out damage, run from those you can't kill, and take enough punishment to stay alive. Intelligence is vital in 3.5 edition D&D because your skill points are based on it, and the more skill points you can get, the better. Intelligence, Wisdom and Charisma are attributes upon which spellcasting abilities depend. Wizards need to have a high Intelligence in order to study and use their spells. They work hard for their array of magics. Wisdom is key for druid and ranger spellcasting. They must be wise in the ways of nature to gain their powers. Charisma decides how powerful bard and sorcerer spellcasters are. Their magics are not based on study or prayers, but on their mystic lineage (sorcerer) or instinct (bard).
There are a great many races that inhabit D&D worlds. Each world is entitled to have the basic races listed in the Player's Handbook (and below). Other established worlds often have different races (or subraces, in 5th edition). Subraces are variations of the core races. For example, the kender of Krynn are based on halflings in most respects but have some dangerous and notable differences, while the drow of Faerun are evil, underground elves with different attributes and abilities, for example.
Once upon a time in D&D, the human race was the only one that could reach full potential in all of the character classes. Elves and other races could not get to the highest levels. This discrimination ended with the inception of 3rd edition. All of the races can aspire to and reach the highest levels in any class.
The human race isn't specialized the way that the other races are; humans don't get many specialized bonuses, don't have a set alignment, and so on. All of the player races besides the human race have unique advantages (and in 3.5 edition, they also have specific weaknesses). These races pass these traits down through the generations. The two notable intermixed breeds, half-elves and half-orcs, have some traits from their parent races. Such inborn strengths often make some races more suited for certain classes (halflings tend to be effective thieves, for instance, because they're naturally small and quick).
The core races are most often discussed in terms of their stereotypes, even in official materials. Stereotypes offer a quick way to get a feel for the various races, without having to play them all. They also reflect the stereotypes that different races often hold about each other's behavior ("Damned prissy elves"). You can make a character that doesn't fit into the typical mold of their race because, while stereotypes may hold true for some, they are by no means all-encompassing, even in D&D. You'll see hints of these stereotypes in my assessment below.
Humans: While humans don't gain many special bonuses, in 3.5 edition they gain extra feats, which is nice (if you're not sure what feats are, click here). In 5e, they start out with an extra point in each of the six abilities, which can be great. In general, most D&D settings are largely populated (or overpopulated) by humans, and they can vary a great deal in culture and training.
Elves: A bit smaller and thinner than humans, with sharper features, elves have a more ethereal appearance. They're the longest lived of the main player races. As a result, they have the time to become powerful and thus make fine wizards; many elven cultures are famous for their great magical works. Elves also have a reputation for revering the natural world, and are commonly rangers and druids.
Half-Elves: Wherever humans and elves live together or near each other, half-elves are bound to spring up, since the two races can reliably breed together. Half-elves don't live as long as elves but are hardier because of their human blood. Reactions to half-elves can vary widely, usually based on how people feel about elves or the human culture they come from.
Dwarves: In D&D, dwarves are shorter and rounder than humans, and weigh more than halfings or gnomes (other small races). They're known as craftsmen and builders, with a knack for working with stone, but also as brave fighters. They're long lived and generally value home, hearth, and kin, but some value wealth over family. Dwarves are often shown as traditionalists who put everything into protecting what they care about.
Halflings: The hobbits of Tolkien's Lord of the Rings books inspired D&D halflings, and it shows. They're smaller than dwarves and elves, and live longer than humans. They're quick, cunning, and enterprising little people. They don't tend to have cities of their own, as they prefer to mix with the races of the world. In most major human cities, there will probably be a few halflings enjoying the crowded streets.
Gnomes: Gnomes are distant genetic cousins to the dwarves but look more like halflings. They often live underground but regularly engage with the surface. They're known as academics, tinkerers, and craftsmen, and having a genuine zest for whatever they do. While dwarves prize sturdy construction and practicality, gnomes often push the limits and value ingenuity.
Half-Orcs: This race really has had it tough in D&D. In previous editions, they were implied to often be the result of rape; in D&D 5e, they're the outcome of using marriage to make peace betweeen humans and orcs. In any case, they tend to be bigger and stronger than humans. While they aren't always evil, they may feel the pull of Gruumsh, the brutal god who created the orcs, and can be terrifying opponents to face.
A character class is a career, a calling and a social role, all rolled into one. The classes are specialized areas of expertise and govern what a character knows how to do. The types of weapons and armor a character can use is dictated by class. The skills a character can know the best are decided by class (in 3.5 edition). Some classes have magic spells available while others don't; different types of spells are available, depending on the type of magic a class can cast (divine or arcane). Your character can keep gaining levels in one class or branch out into others that complement each other. The fighter/mage is a common combination, taking advantage of the fighter's sturdiness and the wizard's spells.
In 3.5 edition, characters can take on prestige classes at higher levels. They become more specialized and can obtain abilities they would not otherwise get from the normal character classes. Characters have to be more advanced, however, before they can qualify for prestige classes, and certain requirements must be met. Prestige classes tend to offer 5 to 10 levels' worth of abilities, and prerequisites can usually be met between 6th and 10th level. In 5th edition, prestige classes aren't in the core rules; you can choose backgrounds or other features to represent something special about your character, instead.
Barbarians, Fighters, Paladins and Rangers are the most proficient with weapons and armor. The other classes know how to use only certain weapons and armor. They are simply not trained as well in such things (although through roleplaying they can learn).
The basic character classes are open to all genders, so it's just as likely to find a female barbarian as a male one. Special circumstances can apply depending on the setting one is playing in, however. Clerics of certain gods might be restricted to one gender or another. It should also be noted that some prestige classes in 3.5 are open only to one gender, as well. A player should inquire about special circumstances that can affect the choice of character class.
Barbarian: The barbarian is a brutal fighter. One is born to a tribe of barbarians, and is steeped in traditions of force and battle lust. Barbarians can fall into a blood rage when they battle and become veritable killing machines. Their rage sets them apart from the rest as much as their world view does. Barbarians have the potential to be some of the most dangerous fighters around.
Bard: In 3.5, the bard is a blend of rogue and wizard, with some unique abilities thrown in. Since they don't usually get to deal the sheer amount of damage a wizard or rogue can inflict and can't take much damage, they can be frustrating to learn to play, at least at first. However, they can be the source of a great deal of fun for the whole party. In general, bards are great for reinforcing the player characters and dealing out sonic-based effects. They also tend to be natural social butterflies, with gifts for deception and intrigue.
Cleric: This class is for the priests of all the gods. While clerics have special domains of magic that their deities grant them, there are basic powers available to all clerics. A cleric can be a healer and confidant, as well as a holy warrior sent to battle evil. A cleric can also be a source of evil, a manipulator and defiler in the name of a dark deity. Clerics of nature-based gods can be maddeningly impartial, allowing nature to take its course. Clerics have a far more personal, powerful, and dangerous religious experience than the average Joe who goes to a temple every week.
Druid: Attuned to nature and wandering through it, druids fight for the protection of wild places with tooth, claw, and magic. They can change their shapes into those of animals, and are granted magic spells and animal allies. Druids are often more at home in the wild with animals than with the races that crowd in cities, but they operate in a variety of environgments; there are desert, mountain and Underdark druids, for example.
Fighter: Your basic fighter is a tough, trained warrior. The abilities of the fighter center around combat. They can't cast magic, but can wield a wide variety of weapons. In 3.5 edition, they can choose more combat-based feats; in 5e, they can take more actions.
Monk: They are trained in the ways of wisdom and war, often in monasteries away from the bustle of the world. They use their bodies to fight and only use peasant's weapons. They come to have great control over their bodies and their hands can be as deadly as weapons.
Paladin: Paladins are the warriors of the gods, above and beyond what clerics can achieve in the arts of arms. They are specially trained, divinely inspired tanks of righteous anger. Paladins can sense evil and have access to some spells. They can smite evil with the concentrated power of goodness and are meant to be on the front line of any holy battle. Paladins are given the full weight of honor, but their deeds have the potential at every turn for becoming the stuff of legends.
Ranger: A ranger is a tracker, woodsman, and warrior who gains specific bonuses when in tune with a particular type of terrain. Rangers also gain access to some spellcasting and bonuses versus specific foes. Rangers tend to dwell in the woods and revere nature like druids but are geared more toward exploring and tracking.
Rogue: They used to be called thieves in 2nd edition; in later editions, they can still steal better than most, but they can do a lot more. They can be spies, saboteurs, assassins, and scouts. Not all rogues are evil, but rogues can be devastating killers because they're trained to aim for vulnerable spots. In 3.5 edition, no other class gains as many skill points as the rogue, so they can also offer a wide array of skills to the party.
Sorcerer: The sorcerer is born with magical potential and learns to use it as time goes by. Sorcerers don't have to study spellbooks to replenish or learn their spells. They can't learn nearly as many different spells as wizards, but they can cast as often (and sometimes more often). Their spellcasting ability is based on Charisma, they may have skills or other abilities based in Charisma, and they can be engaging social characters. In 5th edition, a sorcerer gains special abilities based on the origin of their power, such as a mystical lineage.
Wizard: A wizard's focus in life is magic. Mages study magic a great deal in order to use it, and come to use magic in order to live. They can summon forth minions and can rain down fire on a battlefield, but they rely on memorizing spells in their spellbooks. They're physically weak and yet they can become forces to be reckoned with because with enough time, power, and access, they can learn to cast nearly any arcane spell.
Experience points are awarded to characters as they engage in a campaign's events and overcome challenges, but not every scene will result in an XP award. Some scenes are introductory or informative, without much risk; you probably won't get XP for them, but you'll enjoy other benefits, like information and allies. During the course of a game session, however, characters will face various obstacles and conflicts on the way to their goals. Generally speaking, to gain experience points, something of value has to be at stake, the character has to expend effort, and there's a penalty for failure. Ideally, the characters should succeed at obtaining their goal, although they may still get some XP for partial victory.
In Dungeons & Dragons, dealing with traps and monsters are easy ways to gain XP. This is because each trap and monster already has a certain XP value already assigned to them, so a DM just needs to divide the points between the player characters who took part in the scene. But other knds of encounters such as sneaking into places, stealing goods, solving puzzles, and handling negotiations also earn XP. Since non-combat encounters can vary widely, it's left up to the DM to decide how much XP to give for them. But in the end, experience points represent what a character has learned from participating in a risky encounter where they had something to lose and a goal to pursue - so any scenes that meet those criteria should count.
When a character earns enough experience points, they advance to the next character level and become a little more powerful. Typically, a character only goes up one level at a time and has to go through many more encounters before achieving their next level. New levels bring about more hit points, more spells, more special abilities, and so on. The higher in level a character is, the more things they're able to do and withstand. Characters can become immensely powerful, provided they live long enough.
For instance, if Vik the rogue is idly talking to a bartender at a seedy tavern, there's no struggle and little risk for saying the wrong thing, so no reward will be offered beyond general information he learns from the conversation. But if Vik is trying to get the bartender to tell him where an enemy has gone, then something is at stake. If he fails, he might lose track of his enemy entirely. That doesn't mean the bartender is going to want to part with the information, even if she does know; other patrons might not like a bartender who talks too much behind people's backs. She might have him thrown out of the tavern if he presses too hard. So Vik will have to use what he has - a bribe, deception, diplomacy, intimidation, magic, a sword; it's his choice - to convince her to share what she knows. For the attempt, he should get some XP; whether or not it leads to combat, the scene poses a challenge for him to overcome. If he obtains his goal, he should get the full value of the encounter (which, again, is up to the DM).
You might want to ask your DM if there are any extra reasons that they have for giving XP awards, such as pulling a plan off with style or writing a game journal to keep track of what happened during a session.
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