Why Unix Timestamps?
Unix time counts seconds since Jan 1 1970 00:00:00 UTC — simple, timezone-agnostic, and universally supported. Every database log, API response, and server event you'll ever debug uses it.
Seconds vs Milliseconds?
10-digit timestamps are seconds (1773832716). 13-digit are milliseconds (1773832716000). JavaScript's Date.now() gives ms; most DBs and Unix commands give seconds.
Common SQL log pattern
MySQL stores UNIX_TIMESTAMP() as seconds. To convert in-query: FROM_UNIXTIME(col). PostgreSQL: to_timestamp(col). Paste the number here for instant human reading.
Epoch 0 — the UNIX birth
Timestamp 0 = January 1, 1970 00:00:00 UTC. Negative values go before that. The max 32-bit signed epoch is 2147483647 — January 19, 2038 (the Y2K38 bug).
ISO 8601 vs RFC 2822
ISO 8601 (2025-05-24T10:00:00Z) is the modern standard for APIs and JSON. RFC 2822 (Sat, 24 May 2025 10:00:00 +0000) is used in email headers and HTTP Date headers.