Programmers

The Day of the Programmer is an international professional day recognized in many technology companies and programming firms, that is celebrated on the 256th (hexadecimal 100th, or the 2⁸th) day of each year (September 13 during common years and on September 12 in leap years). The number 256 (2⁸) was chosen because it is the number of distinct values that can be represented with an eight-bit byte, a value well-known to programmers. 256 is also the highest power of two that is less than 365, the number of days in a common year.

From Wikipedia