Occasionally, I have come across Drupal sites that have base64 encoded images embedded into content fields. This is the approach of taking the binary data contained in a file and converting it into a string of characters. The original binary data can then be re-created using this string and the data is understood by lots of different technologies (including web browsers).
Whilst this is technically possible, it massively balloons the size of the database and can often slow down page load times due to the database being slow to respond to the request. Instead of fetching a few kilobytes of data from the table the database is forced to fetch many megabytes of data, which can create a bottleneck for other requests.