What are decimal and binary number systems? How are they different?

The decimal number system (base 10) is what people are most familiar with.  It uses ten digits, 0-9, to represent numeric quantities

The binary number system (base 2) is a two digit system, and uses just 0-1 for representing numeric quantities.

The binary system is used to represent how computers process information – most modern computers use a digital or two-state system to represent data and process it.

An example for these systems: the number 13 in decimal is 1101 in binary.