Mid 20s

The other day my friend Virginia was over and she brought it to my attention that she was now in her mid 20s (she turned 25 in december.) So that leads me to the question .... I am 24 about to turn 25 in February, am I in my mid 20's? I always considered myself in my early 20s still. When do you cross that boundary into the mid 20s? And then from there when do you become in your late 20s? I am starting to feel real old.