Unix Timestamp

Why it is convenient

• One number instead of a complex object — easy to compare, store, pass through APIs
• Timezone-independent — convert to local time on the client
• Date arithmetic becomes integer arithmetic: difference in seconds, add 1 day = +86400

PHP

time();                    // current Unix timestamp
strtotime('2025-01-01');   // string → timestamp
date('Y-m-d', 1735689600); // timestamp → string

// Carbon (recommended)
Carbon::now()->timestamp;
Carbon::createFromTimestamp(1735689600)->toDateString();

The Year 2038 problem

A 32-bit signed integer overflows on 19 January 2038 at 03:14:07 UTC. In PHP with 64-bit integers — no problem. But in old databases with a TIMESTAMP column (32-bit) — there is one.