Base64 Explained in Plain Words
Base64 turns any text — or any file — into a string made only of letters, digits, plus, slash and equals. That matters because many places that move data around, such as email headers and web addresses, were built for plain text and choke on raw binary.
What it is for
Embedding a small image inside a page, carrying a token in a header, or storing binary data in a text-only field. The encoded form is about a third larger than the original, so it is a transport trick, not a compression method.
What it is not
It is not encryption and not a password. Anyone can decode Base64 in seconds, so never use it to hide a secret. If a value must stay private, encrypt it properly and keep the key separate.
How to read the output
Encoded text usually ends with one or two equals signs. Those are padding, added because the input length was not a neat multiple of three bytes. Decoding simply reverses the process and returns the exact original text, including line breaks, when the padding is intact.
Try it with a short sentence first: encode it, copy the result, then decode it back. Seeing the round trip once makes the idea stick far better than any definition.