Hexadecimal is a number system with base-16 similar to how we normally use a base-10 numbering system (0,1,2,3,4,5,6,7,8,9)
Hexadecimal numbers are (0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F)
A = 10
B = 11
C = 12
D = 13
E = 14
F = 15
By convention a hexadecimal number is prefixed with 0x
10 in different numbering systems
Decimal = 10
Binary = 0b1010
octal = 0o12
hexadecimal = 0xA (or 0xa)
You need to be careful with hexadecimal because while 0x10 looks like the number 10 in base-10 it is actually the number 16