What is Unix Timestamp?
The Unix Timestamp (also known as POSIX time or Epoch time) is a system for tracking time as a running total of seconds. This count starts at the 'Unix Epoch'. It is the standard time format used by most computer systems, servers, and databases worldwide.
The Unix Epoch
The starting point is defined as 00:00:00 UTC on January 1, 1970. Dates before this time are represented as negative numbers.
Common Time-to-Seconds Conversions
| Human Readable Time | Seconds |
|---|---|
| 1 Hour | 3,600 Seconds |
| 1 Day | 86,400 Seconds |
| 1 Week | 604,800 Seconds |
| 1 Month (30.44 days) | 2,629,743 Seconds |
| 1 Year (365.24 days) | 31,556,926 Seconds |
The Year 2038 Problem
Similar to the Y2K bug, the 'Year 2038 problem' is expected to occur on January 19, 2038. At this moment, the Unix Time will exceed the maximum value of a 32-bit signed integer. Legacy 32-bit systems may interpret this date as 1901, causing critical errors.
Common Use Cases
Databases
Storing time as integers (INT) saves space and significantly improves query/sorting performance.
File Systems & Logs
Naming backup files or system logs to ensure uniqueness and easy chronological sorting.
APIs & Tokens
Used in JWTs (JSON Web Tokens) to define expiration times (exp claim) and validity periods.