The top three terms are, unsurprisingly: Gulf oil spill, FIFA World Cup, and "Inception," referring to the Leonardo DiCaprio blockbuster film.
We interviewed Twitter co-founder Biz Stone about the list on Friday.
Other top trends included the vuvuzela and Pulpo Paul, the World Cup-predicting octopus. Stone said that nothing was particularly surprising. But when it comes to Twitter trends, he has learned not to be surprised.
Twitter breaks down its list by news event, people, movies, television, technology, world cup, sports, and hashtags.
The top hashtag for the year was #rememberwhen, referring to the trend of users reminiscing about happier times. The full list can be found here.