A number system is a method for writing and representing numbers using digits or symbols in a consistent way. It allows unique representation of numbers and performing arithmetic operations. The main types of number systems are decimal, binary, octal, and hexadecimal, which use bases of 10, 2, 8, and 16 respectively. Number systems are used daily for tasks like making phone calls, budgeting, cooking, using elevators, shopping, and more. [/SUMMARY]