Meme is a greek term that means imitation.
The term is well known and used in the "internet world", referring to the phenomenon of "viralization" of information, that is, any video, image, phrase, idea, music, etc., that spread among multiple users quickly, achieving a lot popularity.
Some examples of very popular memes are the rage faces "Forever alone" and "troll face", whose images represent, respectively, the individual who will always be lonely and the individual who likes to troll the others.
Learn more about the meaning of troll.
The idea of a meme can be summed up by everything that is copied or imitated and that spreads quickly among people. As the internet has the ability to reach millions of people in a few moments, the internet memes they can also be considered as "viral information".
Origin of memes
The concept of "meme" would have been created by zoologist and writer Richard Dawkins, in 1976, when he wrote in the book "The Selfish Gene" (The Selfish Gene) that like the gene, the meme is a unit of information with the ability to multiply, through ideas and information that propagate from individual to individual. Memes constitute a vast field of study in Memetics.
The first meme to be used on the internet was probably created in 1998 by Joshua Schachter, who at the time was 24 years old and worked in the service of weblog called Memepool, where multiple users could post interesting links and share with others.
See also the meaning of fanfic.