According to minecraft wiki:
Griefing is the act of irritating and angering people in video games through the use of destruction, construction, or social engineering. Popularized in Minecraft by teams, griefing has become a serious problem for serveradministrators who wish to foster building and protect builders. Most players tend to dislike and frown upon griefing, while others feel it adds a certain degree of drama to the game. Trolling however, is different from griefing, because afterwards players give their items back, and repair any damage they did.