While away from Apple and working for NeXT, yet another computer company he founded, Jobs picked up a few new tricks — one very important trick in particular: the operating system that would become Mac OS X ("ten" not the letter X). Released in March 2001, and touted as virtually crash-proof, OS X was also easy on the eyes because of its "aqua" look and feel, noted for its soft edges, translucent colors and pinstripes. OS X continued to evolve, going through nine different iterations in ensuing years; its stability, speed and ease of use became a major selling point for new Mac users who switched from Windows-driven PCs.