In literature, one can find many different definitions of the term ‘activist’. Just to quote a couple of them that we found most useful / applicable:

• An activist is a person who diligently and repeatedly tries to achieve some social, economic, or political objective, especially by participation in protest, pressure, organizing, or resistance. (Sharp’s Dictionary of Power and Struggle: Language of Civil Resistance in Conflicts, page 54)
• Activists are at the core of most collective action. Activists are people who care enough about some issue that they are prepared to incur significant costs and act to achieve their goals. Sometimes they act alone, but often they seek to draw others into collective action. (Mobilizing Technologies for Collective Action, Pamela E. Oliver, Gerald Marwell http://www.ssc.wisc.edu/~oliver/PROTESTS/ArticleCopies/MobTechOliverMarwell.pdf)
• An activist is someone who engages in “direct action tactics” [bringing] issues that have been trivialized, passed over, and neglected into direct and immediate importance. (Lee (1984) as quoted in Kramarae & Treichler, 1985, p. 33)
• Activism is action that goes beyond conventional politics, typically being more energetic, passionate, innovative, and committed. (Activism, social and political. Published in Gary L. Anderson and Kathryn G. Herr (eds.), Encyclopedia of Activism and Social Justice (Thousand Oaks, CA: Sage, 2007), pp. 19-27 http://www.bmartin.cc/pubs/07Anderson.html )

In our policy paper on Peace Activism 2.0 we made a differentiation between Activators and Accidental Activists. We think it is still valid to make this differentiation: there is a (big) difference between leaders of the movement (Activators) and followers (Accidental Activists).

Summarised it comes down to:

An Activator is a charismatic idealist, someone with a strong motivation to mobilise people to fight for a certain cause he or she believes in, and to fight against violence and injustice. This struggle comes sometimes with high personal risks. The activist is not running away from these risks though, but is instead persistent, almost militant in achieving his or her goals. A strategic vision, keeping a sharp eye on the end goal, is key and therefore an activist must be flexible, easy adjusting to changing situations, innovative, convincing, and able to build bridges for collective action to achieve political and societal change.

An Accidental Activist is someone with a strong motivation to fight for a certain cause he or she believes in. This struggle comes sometimes with high personal risks. The activist is not running away from these risks though, but is instead persistent in making his or her point. The accidental activist has a specific talent or focus that he or she uses in his or her activism and is not so much focused on broader strategies or abstract goals. In general the engagement of an activist has a limited time span.

Although not automatically a pacifist, a peace activator or peace activist chooses nonviolent methods to prevent or end violent conflicts, to end non-democratic rule, and to organise transition processes that are as peaceful as possible. In his or her strategy for political and societal change, building bridges between antagonist sides is key.

(Peace) Activism 2.0 is ‘upgraded activism’, combining the ‘old methods’ with the (communication) technologies and methods of today, such as (smart) mobile phones, social media, internet based crowd sourcing, crowd funding, and the possibilities of easy and cheap travelling.