Base64 turns binary bytes into text using a 64-character alphabet. It is useful inside text-only systems, but adds roughly one third before compression.
Base64 is representation, not compression
The image codec has already compressed the pixels. Base64 then represents every three binary bytes as four text characters, plus optional wrapper text.
Useful cases
API payloads, email formats, small prototype assets, database debugging, and copy-paste workflows sometimes require text. A Data URI adds the MIME type so a browser knows how to interpret the value.
When to keep a normal file
Large Base64 blobs inflate HTML or JSON, consume memory during decoding, and cannot be cached independently when embedded. Normal URLs are usually better for production page images.