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Learn Number Systems
Short, practical guides to the number systems behind computing — binary, decimal, hexadecimal and octal — plus the ideas built on top of them: bits and bytes, two's complement, ASCII and Base64. Written for students and developers, with real examples you can try in our converters as you read.
What Is Binary?
The base-2 system of 0s and 1s: bits, place value, and how to read binary numbers.
02What Is Decimal?
The base-10 system humans use every day — and why it works the way it does.
03Bits vs Bytes
What's the difference, how storage sizes work, and why a kilobyte isn't quite 1000 bytes.
04How Computers Use Binary
From transistors and logic gates to machine code: why hardware speaks in 0s and 1s.
05What Is Hexadecimal?
Base 16, digits 0–9 and A–F: the compact shorthand developers use for binary.
06What Is Octal?
Base 8, three bits per digit — and why it still shows up in file permissions.
07Binary vs Decimal
Side-by-side comparison with worked conversions in both directions.
08Binary vs Hexadecimal
How nibbles connect the two systems, and the 4-bit grouping trick.
09Two's Complement
How computers represent negative numbers in binary — with a worked example.
10ASCII Explained
How 128 numbers became the alphabet of computing, and where Unicode fits in.
11Base64 Explained
How binary data travels safely through text-only systems like email.
Practice as you learn
Every guide links to the matching converter, so you can test each idea instantly — no sign-up, everything runs in your browser.