We probably use base10 simply because we have 10 fingers
Base >10 systems are called alfanumeric (using letters after running out of digits).
symbols: 0 and 1
Each new digit has a value two times greater than the digit to its right
so 10011011 = 1*128 + 0 + 0 + 1*16 + 1*8 + 0 + 1*2 + 1*1 = 155
symbols: 0-9 and letters a-f for 10-15
Each hexadecimal symbol represents four binary digits (bits), and the primary use of hexadecimal notation is a human-friendly representation of binary-coded values
In Unix and C, prefixed with
0x(e.g.0x2af3). A byte value is in range 0-255 in decimal, and 00-ff in hex.
symbols: A-Z, a-z, 0-9, +, /
Encoding scheme used to represent binary data in an ASCII format, e.g. to turn images into text.
Base64 is not encryption or compression (opposite - ~30% larger files), just encoding.