A Unix timestamp is the number of seconds that have elapsed since January 1, 1970 00:00:00 UTC (the Unix Epoch). It's a universal way to represent time as a single integer, used across programming languages and operating systems.
Timestamps in seconds are typically 10 digits (e.g., 1719446400), while millisecond timestamps are 13 digits (e.g., 1719446400000). This tool auto-detects both formats and converts them correctly.
Unix timestamps are timezone-independent, easy to compare mathematically, compact to store, and universally supported. They avoid timezone and daylight saving time confusion that plagues human-readable date formats.