In general, "griefing" is a term that means action against another player that makes the target feel like being targeted on purpose or for the sake of harassment only.

In EVE, "griefing" refers to various activities, some of which can be argued not to be "griefing" in the classic sense, but parts of valid gameplay.

There are certain forms of griefing that can get you banned from the game. These include (but probably are not limited to) can baiting in rookie systems and certain forms of verbal harassment.

Some types of griefing in EVE

Bump griefing

Bumping refers to ramming your ship into another pilot's in order to throw that ship out of alignment or to push it away from docking or jumping range. This can be used effectively as a combat tactic to stop an opponent from fleeing, but it can also be used simply to grief someone to hell. Ramming another player's ship is not considered to be in violation of the rules and policies of EVE Online.

This tactic is most notably executed at POS bubbles, where capital ships or other slow-moving vessels in particular may be bumped away from the safety of a shield bubble so that they can be tackled and destroyed.

Can flipping / baiting

This refers to the practice of (ab)using the Criminal Flagging System to cause a fight between yourself and an unsuspecting party in high-security space. See main article for more.

Can flipping is officially considered griefing only in Rookie Systems. Some people do it just for fun, without the actual intent to cause the feelings of harassment and frustration in the victim. It is, however, also a typical form of griefing in the classic sense.

Griefer war decs

"Griefer war decs" refers to the practice of declaring a war, typically in high-security, against a party who is not your competitor in politics, regional control, industry, or anything else, and does not want the war. Such wars are often, but not always, declared with the intent to extort money from the victim for termination of the war. While they are sometimes used for actual griefing (ie, declared only for the malicious enjoyment of seeing the victim suffer), they can also be seen as a valid playstyle, and are used by many for simple isk-making and/or combat training.

War declarations are never officially considered griefing and are not a bannable offense, and it has been repeatedly stated by the developers that the possibility for non-consensual PvP is an intended feature.

Suicidegank griefing

Ganking is a common tactic used by griefing pilots whose victims often appear in the same systems, at the same times, or are otherwise easy to find with locator service agents. Pilots who are in competing fields, such as resource harvesting, may frustrate those nearby (whether intentionally or not) by decreasing a product's supply in a system, thereby decreasing other pilots' potential profits. This can quickly lead to plans of retaliation, hence, griefing in the form of suicide ganking.

For most ganks, an agitated party will gather one, two, or several inexpensive ships, fit with modules and charges to deliver the highest DPS possible, and begin warping to the target's location. Upon arrival, the aggressors will try to kill their target(s) before they can warp-out -- and if in high security space, before CONCORD Police can respond. After successful gankings, a co-conspirator will usually loot and salvage the wrecks left behind. In some situations, the instigators extort their victims for ISK in exchange for "safety" from future "incidents." In such griefing, the targeted pilots lose their ships, their modules & cargo, and a significant portion of their wallet as well. While suicide ganking remains a controversial tactic to some pilots, it has been firmly established that it plays an important role in the universe of New Eden.