A 'selfie' is when the photographer is also the subject of the photograph, usually accompanied by a kissy face, or an obscene peace sign gesture. They will often be posted to a social media site e.g. facebook, twitter, instagram, etc.
"Did you see Beiber's selfie on facebook?"
"Nah, gurl, ain't nobody got time for dat!"
The act of one taking a photo of oneself and possibly others and then "posting it" on some sort of so called, "social media"
Sara-But first let me take a selfie! (takes a photo of herself and posts it on Instagram)
Hana-Ew you take selfies?!
Sara-Hells yeah!
Hana-(walks away)