What is Unix Epoch Time?
The Unix epoch (or Unix time) is a system for describing a specific point in time. It is defined as the number of seconds that have elapsed since January 1, 1970 (Midnight UTC), not counting leap seconds.
Why Do Developers Use It?
Storing dates as a single unified integer across databases (like MySQL or MongoDB) prevents massive headaches regarding timezone formatting, Daylight Saving Time skips, and string parsing errors. When every server worldwide agrees that a purchase happened at exactly 1712845200, local browsers can mathematically parse that number down into proper local jurisdictions flawlessly.
Seconds vs Milliseconds
Most backend languages (like PHP, C++, Python) natively utilize Unix time in Seconds (10 digits). Conversely, JavaScript's native Date.now() API operates in Milliseconds (13 digits). This tool intelligently parses how long the requested integer string is to assume whether you are processing standard Seconds or JS Milliseconds, preventing erroneous 1970 dates.
The Y2K38 Problem
Similar to the famous Y2K bug, computers storing Unix time in 32-bit signed integers will run out of space to represent the number on January 19, 2038. This will cause the timestamp to loop negatively back into the year 1901, severely breaking older un-patched server architecture.