Base64 is an encoding scheme that converts binary data into a text format using 64 ASCII characters (A-Z, a-z, 0-9, +, /). It is commonly used to transmit binary data over text-based protocols like email or HTTP. Base64 is not encryption – it is just encoding. Anyone can decode Base64 data. Common use cases include encoding images in CSS, transmitting data in JSON APIs and storing binary data in text files.