Just for those who may be confused, no, no, it is not a 'rap'. Think wrapping presents and you're on the right lines.
Meaning & EtymologyEdit
It's a wrap means this is successfully completed. Based on the literal meaning of it's a wrap (the filming of this movie or part of a movie is completed)
Use in Normal SpeechEdit
To say that a task is finished.
"After three months of planning and two years of building, it's a wrap and we've moved into our new home."
Same use, but in the past tense.
"It was a wrap for the latest unmanned mission to Mars."