History of ASCII art
Relying mainly on computers for presentation, ASCII art is an artistic medium making images from piecing together any of the 92 (of the available 128) characters in various combinations. Prominent in the early days of the Internet due to its low file size in comparison to images, people would map out pictoral representations using ASCII art as a more customisable, compatible alternative to images.
Today, the medium is used for more elaborate creations such as webs comics, as in this example, animations, as demonstrated here and even desktop art (example here). In the example above right, some block ASCII is shown in two different font sets, demonstrating the slight difference across formats. This makes it less compatible than photographs with regards to consistency. The block method, however, allows for more intricate and smoother-looking art whilst retaining the jagged edged pixellated look characteristic of the medium.
ASCII stereograms, meanwhile, attempt to recreate 3D effects using ASCII. These can be compared to early computer games and their fascination with achieving a pseudo-3D effect using minimal polygons. Taking simple data from an ordinary stereogram, these are converted into the lower-res format for ease of transmission.