What is SGVsbG8gV29ybGQ=?

Explanation

SGVsbG8gV29ybGQ= decodes to the text Hello World. It appears in countless tutorials and documentation pages.

"Hello World" is 11 bytes long. Base64 works on groups of 3 bytes, so the last group contains only 2 bytes and needs one = padding character.

You can decode any similar value yourself with the Base64 decoder, or identify a file from its first characters with the Base64 to File converter.