Unix Timestamp

Unix timestamps provide a universal, timezone-independent way to represent time.

Key characteristics

• Integer count of seconds (or milliseconds in some systems).
• Always in UTC (no timezone offset).
• Same value globally at any given moment.
• Easy arithmetic for time calculations.

Common formats

• Seconds: 1609459200 (10 digits).
• Milliseconds: 1609459200000 (13 digits, JavaScript).
• Microseconds: Used in high-precision systems.

Use cases

• Database timestamp storage.
• API response timestamps.
• Log file entries.
• Cache expiration times.

Gotchas

• Year 2038 problem (32-bit signed integer overflow).
• Leap seconds not accounted for.
• Conversion errors between seconds/milliseconds.