The Day of the Programmer is celebrated on the 256th day of the year. Usually, that is September 13th, but every leap year (like 2016) it’s September 12th. The number 256 (2 to the power of 8) was chosen as it represents the possible amount of different values that can be encoded into an 8-bit byte and is less than the number of days in a year.
The Day of the Programmer has become an official holiday only recently — in 2009, Dmitry Medvedev signed the order for it. The idea itself was around since 1996 — it was brought up by the head of the Computerra publishing house. For several years, this holiday was celebrated informally.
There is one more programmers holiday in Russia — 22nd of April, or 22.04. It derived from the «Software in Computer Engineering and Automated Systems» program's code official listings — 220 400.
Nevermind the jokes about bathing in fountains (that's what paratroopers do on their official holiday), the Day of the Programmer is calm and peaceful. IT-companies usually celebrate it with different events and parties where they conduct contests and play pranks.
ITMO University's team congratulates all Russian programmers with their professional holiday! We wish you green tests, closed tickets and pull quests on github! Good luck!