@o_e_l_e_o, this has been the first time I ever known anything like Unix, I checked the site and saw the Unix format and able to convert real date to the Unix format, it is quite exciting to know about this.
It is widely used in the back end of electronic devices, computers, phones, etc., although most software will convert Unix time stamps to human readable date formats prior to displaying them. It is simply the number of seconds since 00:00:00 on 1st January 1970 UTC. It has the bonus of being unaffected by timezones, so is the same for everyone in the world at all times. It also ignores leap seconds, so every day Unix time increments by exactly 86,400. Now, an interesting quirk for bitcoin. Unix time suffers from what is known as the Year 2038 problem. Most systems store Unix time as a 32 bit signed integer, meaning the values run between -231 and 231-1. This means that they will hit their maximum possible value of 231-1 at 03:14:07 on 19th January 2038 UTC, causing them to overflow and experience an error. Bitcoin, on the other hand, stores Unix time as a 32 bit unsigned integer, meaning the values run between 0 and 232-1. This means that bitcoin won't experience this bug until 06:28:15 on 7th February 2106 UTC.
) is any value below 500,000,000 is considered as a block height, and any value from 500,000,000 upwards is considered as a Unix time stamp. See here: 