Date to Unix Timestamp

Converting a date to a Unix timestamp is the inverse of Unix timestamp decoding. Given a human-readable date like "2024-01-15 12:00:00 UTC", the corresponding Unix timestamp is the number of seconds between that moment and the Unix epoch (January 1, 1970, 00:00:00 UTC). This conversion is needed when constructing API requests that require timestamp parameters, writing SQL queries with date range conditions using epoch values, setting expiration times in JWTs or cookies, configuring cron jobs and scheduled tasks, and comparing dates in scripting languages that work natively with timestamps. Timezone handling is critical: the same date string represents different timestamps depending on whether it is interpreted as UTC or local time.