Fast-forward 10 or 20 years. For decades, your life is on your
computer: recordings, family pictures, writings, address book,
recordings, and on and on.
Can you access them?
There's format. Some formats are open enough that there will
always be working tools; , others aren't. Can you open your
old MS Word documents? Can you play your .aac music
files?
Also: organization. Will iPhoto still be around to read the
file structure? Will your cloud storage provider still be in
business? Where exactly are these files?
And: backup. We all struggle with that.
Best guesses:
If you can read it in a text editor, you're good.
.txt, vanilla plain text ascii, is awesomely simple and solid.
Suitable for journal entries, notes, computer code.
.html and .rtf are simple markup and
pretty safe.
.pdf is probably ok, but less clearly so.
.doc* makes me nervous.
.wav and .aiff are uncompressed and totally
safe.
.mp3 has made the leap to universal/nearly open and I
trust it to be readable indefinitely. Also mp3's
keep metadata right in the file, so go ahead and edit it the
way you like it; it'll survive.
.aac MUCH LESS CLEAR. I strongly suggest changing
the default import settings in iTunes to convert
to mp3 at highest quality.
.jpg's are compressed but, like mp3's,
pretty safe.
.tiff is uncompressed and thus safe.
I prefer .png to .gif where possible.
Photoshop format I don't completely trust.