The document explains four types of number systems: binary (base-2), octal (base-8), decimal (base-10), and hexadecimal (base-16). The binary system uses two symbols (0 and 1), while octal uses digits 0 to 7, decimal employs ten digits including 0-9, and hexadecimal includes 0-9 along with letters a-f. Each system has its own application and advantages in computing and mathematics.