Convert between Unix timestamp and date
Unix timestamp (also known as epoch time or POSIX time) is the number of seconds that have elapsed since January 1, 1970 00:00:00 UTC, not counting leap seconds.
Unix timestamps are commonly used in programming and databases because they are:
• Universal - Same everywhere, regardless of timezone
• Simple - Just a single number
• Easy to compare - Simple integer comparison
• Compact - Takes less storage than date strings
• Seconds - Most common format (10 digits for current dates)
• Milliseconds - Used by JavaScript (13 digits)
• Microseconds - High precision (16 digits)
• Nanoseconds - Very high precision (19 digits)