This design focused brand name is based on the word "pixel" / "pictures".
The name "pix" has only three characters and only one syllable. Mono-syllable names are extremely rare and exceptionally desirable. One syllable names are used by established brands like Nike, Ford and Box.
Pix.me is a .me domain.
This domain was first registered in April 2008. Older domains have an advantage when ranking in search engines.