Base64 is a binary to ASCII encoding scheme. Previously it's known as printable encoding, but later in June 1992 it called as Base64. Base64 encoding schemes are commonly used when there is a need to encode binary data that needs to be stored and transferred over media that are designed to deal with ASCII. This is to ensure that the data remain intact without modification during transport.
Well Base64 is often used in cryptography which is not a secure mechanism. Base64 is not an encryption algorithm and hence no to be used to hash passwords or encrypt sensitive data, because the encoded data can be easily decoded