Slacktivism is taking social action online in ways that involve little personal effort and have little immediate effect; the word is a portmanteau of slacker and activism.
PC philanthropy, for example, involves donating unused computing resources to benefit a social cause. For the user, this typically means downloading a small program that detects idle time and starts using compute resources until they are required again. Other examples of slacktivism include sharing and promoting content about issues through Facebook, Twitter and other social platforms, joining organizations without contributing significantly, boycotting abusive organizations and signing and sharing online petitions.
Slacktivism is often disdained because of the minimal effort that it requires and the idea that those minimal efforts may make people less likely to take more substantive and effective actions. Nevertheless, online media and social media in particular have made it possible to raise awareness about social issues in a way that has never been possible before. According to proponents, the collective small acts of online activism can be effective in sharing information about important issues, galvanizing public awareness and political will and, ultimately, bringing about change.
See Dr. Melissa Langdon's TEDx talk, "Transforming slacktivism into activism."