What is a Social Justice Warrior or SJW?

Answer 1

One who believes in the necessity of proper treatment of all peoples, withholding prejudice based on gender/race/etc... though commonly the title is used improperly by those who wish to justify their own beliefs while they only loosely apply their own morals preached. To be a SJW one walks a fine line where they must remain vigilant to the errors of society while observing themselves constantly for faults.

Notable social justice warriors include: Anita Sarkeesian, Julie Zeilinger and John Green along with many more

-Sam.H

Answer 2

Simple Answer
An SJW or Social Justice Warrior is a pejorative term used for a person who comments on the internet and Social Media in support of "social justice", which is a smattering of politically correct initiatives to overturn instances of "racism" and "triggering".

Longer Discussion
The fundamental ideological construct underlying the SJW phenomenon is the idea that privilege attaches to certain people and that fighting this privilege is the best way to promote equality of all people. The only problem is that SJWs see privilege as a construct based on race, gender, sexual orientation, religion, ethnicity/national origin, weight class, and other protected classes rather than seeing privilege as a result of (1) wealth, (2) social prestige, (3) education, (4) hard work and perseverance, (5) personal connections, (6) attractiveness (both physical and behavioral), (7) personal values, and/or (8) interpersonal skills. This effectively turns into SJWs into racists/sexists/etc. since their primary goal is to overturn racial/sexual distinctions in all parts of society, regardless of whether such distinctions exist because of merit and personal choices as opposed to discrimination. Deriving from this is the famous SJW phrase, "Check your privilege", which refers to the SJW concept that people who happen to be in the majority categories of race/sex/religion/ethnicity, etc. should stop voicing opinions contrary to those they assume that minority individuals in those groups have. This completely serious Buzzfeed Article allows a person to compute his "privilege score" by taking into account his racial/sexual/religious/ethnic, etc. identity, but not his wealth, social prestige, values, and other actual markers of privilege.

Secondly, SJWs are known for using the phrased "triggered" or "triggering" to refer to speech that they believe other people (usually a racial, sexual, religious or ethnic minority) will find offensive. Triggering statements can include anything from actual offensive statements to discussions of scientific or survey data that oppose their conception of reality. A "triggered" SJW in real life, as can be seen across YouTube in the numerous protests by SJWs against conservative political speakers on college campuses, will often scream, cry, use bullhorns, violently attack people with dissenting opinions, and any other form of a heckler's veto in order to prevent the "triggering words" from reaching anyone's ears. Far more depressing is that often-times when asked to pinpoint what specific offensive language they are protesting, they have no answer, primarily because they have not listened long enough to hear what the "offensive" person has to say to know what it is that they do say and be offended by it.

Finally, SJWs are known for the habit of "virtue signalling", which is when an SJW will simply repeat points from whoever is the most popular blogger or commenter of the moment, especially on Social Media sites like LiveJournal or Tumblr, hoping that they will gain importance in the community and become popular in return. This repetition shows that they are adopting the "correct" stance on key issues. Since virtue signalling is very popular in the SJW community, they will often dogpile on a celebrity that recently said anything "triggering".