what is BASE-64 encoding?

What does Base64 mean?

It is one of the oldest ways to encode things into html (first proposed in 1987!). It is a way of turning different types of data into a series of letters and numbers that is safe for HTML. One of those data types is images.

Base64 is an encoding and decoding technique used to convert binary data to an American Standard for Information Interchange (ASCII) text format, and vice versa. It is used to transfer data over a medium that only supports ASCII formats, such as email messages on Multipurpose Internet Mail Extension (MIME) and Extensible Markup Language (XML) data.

Base64 is also known as Base64 Content-Transfer-Encoding.

Explains Base64

Base64 is a binary to text encoding scheme that is generally used to transfer content-based messages over the Internet. It works by dividing every three bits of binary data into six bit units. The newly created data is represented in a 64-radix numeral system and as seven-bit ASCII text. Because each bit is divided into two bits, the converted data is 33 percent, or one-third, larger than the original data.
Like binary data, Base64 encoded resultant data is not human readable.
Many people are not aware that images can be inlined into html code. The method in which this is done is called base64 encoding.
Base64 encoded images become part of the html and displays without loading anything instead of a web browser having to download the image.

To turn an image into base64, you can use the tool I made for that purpose here - Base64 image encoder or just search for "base64 image encode" there are many tools out there.