  Social media users give rise to social trends as they share about common
interests, which can be triggered by different reasons. In this work, we
explore the types of triggers that spark trends on Twitter, introducing a
typology with following four types: 'news', 'ongoing events', 'memes', and
'commemoratives'. While previous research has analyzed trending topics in a
long term, we look at the earliest tweets that produce a trend, with the aim of
categorizing trends early on. This would allow to provide a filtered subset of
trends to end users. We analyze and experiment with a set of straightforward
language-independent features based on the social spread of trends to
categorize them into the introduced typology. Our method provides an efficient
way to accurately categorize trending topics without need of external data,
enabling news organizations to discover breaking news in real-time, or to
quickly identify viral memes that might enrich marketing decisions, among
others. The analysis of social features also reveals patterns associated with
each type of trend, such as tweets about ongoing events being shorter as many
were likely sent from mobile devices, or memes having more retweets originating
from a few trend-setters.
