The defined beginning of Unix time, at 00:00:00.

Unix time is a date and time representation widely used in computing. It measures time by the number of non-leap seconds that have elapsed since 00:00:00 UTC on 1 January 1970, the Unix epoch. For example, at midnight on 1 January 2010, Unix time was 1262304000.

January 1 is the first day of the calendar year in the Gregorian Calendar; 364 days remain until the end of the year. This day is also known as New Year's Day since the day marks the beginning of the year.