What is Unix Time?
Unix time (also known as POSIX time or UNIX Epoch time) is a system for describing a point in time. It is the number of seconds that have elapsed since the **Unix Epoch**, minus leap seconds. The Unix Epoch is **00:00:00 UTC on 1 January 1970**.
Because Unix time is a single integer, it is incredibly efficient for computers to store and compare. Whether you are developing a distributed database or a simple mobile app, Unix timestamps are the universal language of temporal data.
The "Year 2038" Problem
On January 19, 2038, 32-bit Unix timestamps will overflow. This is similar to the Y2K bug. Most modern systems have already migrated to 64-bit integers, which can represent time for the next 292 billion years.
Milliseconds vs Seconds
While the standard Unix timestamp is in seconds, many platforms (like JavaScript and Java) use **milliseconds**. If your timestamp has 13 digits instead of 10, it is likely in milliseconds.
Programming Examples
// Current timestamp in seconds
const seconds = Math.floor(Date.now() / 1000);
// Convert to Date object
const date = new Date(seconds * 1000);import time
from datetime import datetime
# Current timestamp
ts = time.time()
# Convert to readable format
dt = datetime.fromtimestamp(ts)
print(dt.strftime('%Y-%m-%d %H:%M:%S'))Frequently Asked Questions
Does Unix time include leap seconds?
No. Unix time ignores leap seconds, which is why it is not a perfect linear representation of time, but it is extremely practical for computing.
What happens at timestamp 0?
Timestamp 0 corresponds to exactly January 1, 1970, at 00:00:00 UTC.