Number bases (radix systems) represent the same integer with different digit sets and place values. Binary uses two digits, decimal ten, hexadecimal sixteen. Convertitive performs all base conversions using arbitrary-precision integers (BigInt), so results are exact for any size — including 64-bit and 256-bit values that overflow a JavaScript Number.
Binary (base 2) represents numbers with two digits: 0 and 1. It is the native language of every digital computer because each digit maps directly to a transistor's on/off state. A group of 8 binary digits forms one byte, the smallest addressable unit in most modern hardware.
Octal (base 8) uses the digits 0 through 7. Each octal digit represents exactly three bits, which is why octal was widely used on early minicomputers and is still the conventional notation for Unix file-permission masks (e.g. 755).
Decimal (base 10) is the everyday number system, using the digits 0 through 9. It is the default base for almost all human-facing numbers — from prices to phone numbers to scientific measurements.
Hexadecimal (base 16) uses digits 0–9 plus the letters A–F to encode the values 10–15. It is the dominant compact notation for binary data: every two hex digits represent exactly one byte. Used universally for memory addresses, color codes (#RRGGBB), and cryptographic hashes.