This document introduces basic concepts of digital electronics. It discusses that digital electronics deals with binary numbers (0 and 1). It also covers number systems like binary, octal, decimal, and hexadecimal. Finally, it demonstrates different methods of number conversion between these systems - such as decimal to binary, binary to decimal, and converting between different bases like hexadecimal to octal. Conversions are performed by dividing or multiplying by the base and writing the remainders in reverse order.