What Is Roleplaying?
Roleplaying is making decisions from the viewpoint of a fictional character in the world in which your game takes place. That character may or may not resemble you, personality-wise, and certainly a lot of the situations in which he or she finds him- or herself will bear little resemblance to any you have encountered. You are playing that role to the extent that you make decisions on the basis of what that character would do in that situation, as opposed to the many other reasons you might make such decisions.
(Some examples of the latter: what is tactically optimal [though no character without a death-wish will entirely ignore this], what seems "cool", what will make for the best story, what you think the GM wants you to do, what you think the GM doesn't want you to do, what will most entertain the group, what will make the quieter players feel included, what will get the current scene over with the soonest. There is a legitimate place for all of these things, and none of them are incompatible with roleplaying, but none of these should routinely be the main reason behind your decisions at the expense of doing what your character would do.
Moreover, there are times when roleplaying your character properly is a very bad idea. But in most of the ones I’ve seen, it’s because something went wrong at character creation. Everything in this mini-essay assumes that your character is (a) reasonably interesting and (b) not too much of a dick. Faithfully roleplaying an asshole character can wreck a whole campaign; the solution, however, is to not make your character an asshole, or failing that, to exercise great care and subtlety about how you do so.)
Notice what I haven't mentioned, and that's acting out dialogue in-character and so on. That's nice when it's done well, but it's not the same thing as roleplaying. You can roleplay without acting and you can act without roleplaying. The player whose character has a Charisma of 8 but uses his own forceful personality to constantly dominate every scene with dialogue will usually claim he is the main roleplayer in the group. He is wrong. He is doing lots of acting, but virtually no roleplaying. He is making no serious attempt to play the character that's written on his character sheet, or is doing so only when it is convenient for serving some other agenda. (In fact, he’s cheating, in the same way he would be if the character had a Strength of 8 but he gave himself a +3 bonus instead of a -1 penalty on his melee combat rolls.) On a related note, pressure is often unfairly put on more introverted gamers to "roleplay more" when they may already be doing more roleplaying, though admittedly far less acting, than the more extroverted players doing the admonishing.
Having said that, the more overt voice-actor types can be more entertaining to have around. But this is by no means a universal law. Watching someone with no talent for it constantly try their hand at such voice-acting is more painful than stepping on a d4. Being constantly pushed around by the one guy who is good at it is worse still. And one tires of even the more benign voice-actor types, if they overdo it. There is a limit to how much acting is a good thing. (There is also a limit to how much role-playing is a good thing, but - unless you’ve deliberately designed a character who’s an asshole - it’s a lot harder to reach and, often, a lot easier to reconcile with other legitimate concerns, like a reasonably equitable split of spotlight time.)
Roleplaying, so defined, is not the be-all and end-all of role-playing games. But it is one of the main three things - the others are being open-ended and non-competitive - that separate those games from wargames and boardgames. It does not require talking in a funny accent, but it does involve getting into a slightly different mentality than most other sorts of games call for. I think it's a big part of what makes the hobby so rewarding, though there are places (I've listed several in the second paragraph) where doing an end-run around it is sometimes justified. There is nothing wrong with killing things and taking their stuff, but it's more fun to kill things and take their stuff in a context, and while roleplaying as most people define it may or may not serve that end, roleplaying as defined above is the very thing that makes it possible.
(Some examples of the latter: what is tactically optimal [though no character without a death-wish will entirely ignore this], what seems "cool", what will make for the best story, what you think the GM wants you to do, what you think the GM doesn't want you to do, what will most entertain the group, what will make the quieter players feel included, what will get the current scene over with the soonest. There is a legitimate place for all of these things, and none of them are incompatible with roleplaying, but none of these should routinely be the main reason behind your decisions at the expense of doing what your character would do.
Moreover, there are times when roleplaying your character properly is a very bad idea. But in most of the ones I’ve seen, it’s because something went wrong at character creation. Everything in this mini-essay assumes that your character is (a) reasonably interesting and (b) not too much of a dick. Faithfully roleplaying an asshole character can wreck a whole campaign; the solution, however, is to not make your character an asshole, or failing that, to exercise great care and subtlety about how you do so.)
Notice what I haven't mentioned, and that's acting out dialogue in-character and so on. That's nice when it's done well, but it's not the same thing as roleplaying. You can roleplay without acting and you can act without roleplaying. The player whose character has a Charisma of 8 but uses his own forceful personality to constantly dominate every scene with dialogue will usually claim he is the main roleplayer in the group. He is wrong. He is doing lots of acting, but virtually no roleplaying. He is making no serious attempt to play the character that's written on his character sheet, or is doing so only when it is convenient for serving some other agenda. (In fact, he’s cheating, in the same way he would be if the character had a Strength of 8 but he gave himself a +3 bonus instead of a -1 penalty on his melee combat rolls.) On a related note, pressure is often unfairly put on more introverted gamers to "roleplay more" when they may already be doing more roleplaying, though admittedly far less acting, than the more extroverted players doing the admonishing.
Having said that, the more overt voice-actor types can be more entertaining to have around. But this is by no means a universal law. Watching someone with no talent for it constantly try their hand at such voice-acting is more painful than stepping on a d4. Being constantly pushed around by the one guy who is good at it is worse still. And one tires of even the more benign voice-actor types, if they overdo it. There is a limit to how much acting is a good thing. (There is also a limit to how much role-playing is a good thing, but - unless you’ve deliberately designed a character who’s an asshole - it’s a lot harder to reach and, often, a lot easier to reconcile with other legitimate concerns, like a reasonably equitable split of spotlight time.)
Roleplaying, so defined, is not the be-all and end-all of role-playing games. But it is one of the main three things - the others are being open-ended and non-competitive - that separate those games from wargames and boardgames. It does not require talking in a funny accent, but it does involve getting into a slightly different mentality than most other sorts of games call for. I think it's a big part of what makes the hobby so rewarding, though there are places (I've listed several in the second paragraph) where doing an end-run around it is sometimes justified. There is nothing wrong with killing things and taking their stuff, but it's more fun to kill things and take their stuff in a context, and while roleplaying as most people define it may or may not serve that end, roleplaying as defined above is the very thing that makes it possible.