What is the Unix timestamp?

The Unix timestamp is the number of seconds that have passed since 00:00:00 UTC on Thursday, 1 January 1970, not counting leap seconds. It’s one way of tracking time as a running total of seconds.

For example, in JavaScript you can get the current time as a Unix timestamp as follows;

console.log(Date.now() / 1000)
// Outputs something like "1703588202.651"

In PHP, you can do:

echo time();
// Outputs something like "1703588373"