The RFC 2822 format is a date notation common in email headers and HTTP responses, looking like Mon, 15 Jan 2024 09:30:00 GMT. Its hallmark is the English abbreviations for weekday and month.
In JavaScript, the string produced by date.toUTCString() is essentially this format, and HTTP's Date, Last-Modified and Expires headers use it.
It's easy for humans to read, but string sorting doesn't match chronological order, so Unix timestamps or ISO 8601 are better for storing and comparing. AG TIME also includes the RFC 2822 (UTC) form in its conversion results so you can grab a header value directly.