[link]
ANSI is not pixel art. The blocks you see are characters (i.e. text, hence "textmode art"). The ANSI palette consists of 16 pre-determined foreground covers, with 8 optional background colours for each character. Coloured characters or "blocks" are manually laid down on a grid typically 80 units wide by however many long.
Although it is extremely time-consuming, a certain kind of magic can be achieved within these limits...
Here are some links to other ANSI artists on DA:
taintedXL [link]
BYM [link]
zeroVision [link]
m1sfit [link]
mimic (group) [link]
jSepia's page is also a good nexus for finding about all things text art related [link]
One may also witness the kinds of rubbish mistakenly filed under ANSI here at DA by visiting the category page for the medium:
[link]
FINAL NOTE: ALWAYS VIEW ANSI IN FULL!!!