Most systems don't store 2:30 PM — they store a number, a count of seconds since a fixed reference point, and format it as a readable date only when something needs to display it. That number is a Unix timestamp, and understanding it explains why timestamps look the way they do, why time zones don't attach to them directly, and how tools like cron use plain numbers to schedule work.
This category is for anyone working with timestamps, date formats, or job scheduling in code: what a Unix timestamp is, why the count starts in 1970, how to turn a timestamp into a readable date, how the ISO 8601 format standardizes dates across systems, and how to write a cron expression to schedule a recurring job. Each guide includes the concrete syntax and worked examples, not just the theory.
Start with the Unix timestamp guide if the concept is new. If you already understand timestamps, jump to conversion, ISO 8601, or cron syntax directly.
Start here
New to the topic? Read What Is a Unix Timestamp? A Developer's Guide first — it's the cornerstone of this category and covers the concept the rest build on.
All guides in this category
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Category FAQ
Which post should I read first?
Start with What Is a Unix Timestamp? It's the cornerstone of this category and covers the concept every other post assumes.
What does the Developer Time & Timestamps category cover?
What Unix timestamps and the Unix epoch are, how to convert a timestamp to a readable date, the ISO 8601 date format, and how to write a cron expression.
Do I need to read these in order?
No. Each post answers its own question and stands alone. Read the one that matches what you need right now; the guides link out to each other where it's relevant.