You may have heard the term "meta-gaming" and wondered what, exactly, it means. Meta-gaming is a trend whereby knowledge you have acquired as a player is used by your character for whatever gain. For example, if you had read the character profile of a necromancer from Nabher named Jaleb Har, and your character possesses no in-game knowledge of the information, in chat you can't just go and post:
De'Lukas Rauschenberg says, "Jaleb Har, I know you. You are a necromancer who resides in the city of Nabher."
If De'Lukas has not encountered Jaleb Har in chat before or discovered these facts in-game, then he clearly cannot utter such a thing (no matter how silly it sounds). You may reason unusual instances where such knowledge could be glistened—what if your character was a psychic and had discovered the facts through the use of innate abilities, you ask? Take De'Lukas himself. He is actually a supernatural painter, and may have uncovered these facts while manufacturing a new painting of some mystical import. In role-play, anything is possible. Yet . . . would it even then be permissible for you to have your character declare such revelations?
You Know It Makes Sense
It wouldn't, at least not without clarification. While it may seem acceptable—and you may even have set out to describe, using detailed posts, preparation of your characters' discovery—Jaleb Har in this case may be able to conceal his thoughts and whereabouts by magical means. Being a necromancer, he may possess magical powers and wards to prevent detection of his person and whereabouts. Your post, if made blindly, may prove to be invalid.
The golden rule: before you assume anything, for purposes of play, initiate a one-to-one private discussion with the player (or through the GM and the player) and clarify the issue. Ask, "Can my character discern these facts about your character, blah blah blah, using an innate ability, blah blah blah?" The answer may be yes, making the post quite acceptable.
Meta-gaming can easily (and usually will) be taken in the wrong light and be deemed discourteous or just plain ignorant.
Cheating is Bad
If you stop to think about it, you could believe many gamers are susceptible to meta-gaming. There are many meaningful undertakings where gamers intentionally cheat, given the allure of popularity and prospect of enhancing their own character position and power. After all, if you know a certain something, and you use that knowledge to your characters' advantage, he or she can gain much.
One can follow cheating into a dark hole which is infinitely deeper, more subtle and discreet. It can be all too easy for a role-player to take it for granted that their character has the requisite knowledge and experience to perform certain actions and duties, to an extent that potential role-playing passages are bypassed or ignored completely. Facets of information can remain inconspicuously absent from character profiles, uncharted elements which arise in times of the player's need. This can be viewed as an easy way out of additional role-playing, a means to abandon uninteresting side-scenes of education, a way for a player's character to survive pain and obstacles, or to gain the upper hand in dialogue.
Taking Positives
To be fair, all that is purposeful of intent is not necessarily down to cheating or leading to broken player integrity. At times respect the player's need because other constraints invariably impose themselves on the game and the players, chiefly those like play time. The duration of time you can spend in a chat session may dictate the need for a "quick fix," that a particular scenario can be passed by to get the game moving quicker or with greater fluidity.
Perhaps a great motivation today is the inherent need to inspire interaction among characters. Consider engineering interaction with another player. What would happen if you were to ask another gamer, "Can my character, by default, ‘already' know your character? It would help stir something up . . . ."
With the consent of the other player, your character has a new ally (or enemy) who, in all honesty, they did not previously know. This could be considered by some poor play, and it is if done in a manner lacking proper respect (to team up and kill another character for example). If such actions are however taken by the player and all associated with the best of intentions at heart, and for the purposes of good role-play and storyline, is this seemingly so bad? Always remember the rather obvious "get-out" clause: that at some date in the past (or future if you time travel), the characters were introduced to one another, and therefore actually do know one another. Such a tactic can present a game, and interaction, for another time.
Necessary Contrivance
Always remember that the best role-players in the game, even the GM, use time and other tools in such a fashion so as to manipulate and contrive new passages of role-play. There are many methods of tying strands of game together into a greater web of play. Be aware that plot contrivance is very necessary—for every writer and role-player—to keep things healthy, moving and flowing with a sense of purpose and innovation in the game. Doing so may lack true spontaneity for the creator of such devices, but the rails will be well-oiled if proper planning and considerations are made. Then the mine cart rumbles off and the fun begins for everyone involved.