Meme

Rihanna takes on fat-shamers with the perfect meme

http://edition.cnn.com/2017/06/06/celebrities/rihanna-response-body-shaming-meme/index.html?iid=ob_lockedrail_bottommedium

Q1: Would anyone please explain what 'meme' means in this context? I've looked it up on my dictionary and Wikipedia, but I'm unable to understand.

Q2: And what are the meanings for H2, H2, PRE, which are the editing functions on a post? What are H, PRE stand for?

Many thanks!

PS.

A meme (/'mi?m/ MEEM), a https://en.wikipedia.org/wiki/Neologism coined by https://en.wikipedia.org/wiki/Richard_Dawkins,^{https://en.wikipedia.org/wiki/Meme#cite_note-cream-1} is "an idea, behavior, or style that spreads from person to person within a culture".^{https://en.wikipedia.org/wiki/Meme#cite_note-2} A meme acts as a unit for carrying https://en.wikipedia.org/wiki/Culture ideas, symbols, or practices that can be transmitted from one mind to another through writing, speech, gestures, rituals, or other imitable phenomena with a mimicked theme. Supporters of the concept regard memes as cultural analogues to https://en.wikipedia.org/wiki/Gene in that they self-replicate, mutate, and respond tohttps://en.wikipedia.org/wiki/Natural_selection.^{https://en.wikipedia.org/wiki/Meme#cite_note-3}