
Snowflake ID

Snowflake IDs, or snowflakes, are a form of unique identifier used in distributed computing. The format was created by Twitter and is used for the IDs of tweets. The format has been adopted by other companies, including Discord, and Instagram, which uses a modified version.
Format.
Snowflakes are 64 bits. The first 41 bits are a timestamp, representing milliseconds since the chosen epoch. The next 10 bits represent a machine ID, preventing clashes. Twelve more bits represent a per-machine sequence number, to allow creation of multiple snowflakes in the same millisecond.
Snowflakes are sortable by time, because they are based on the time they were created. Additionally, the time a snowflake was created can be calculated from the snowflake. This can be used to get snowflakes (and their associated objects) that were created before or after a particular date.
Usage.
The format was first announced by Twitter in June 2010. Due to implementation challenges, they waited until later in the year to roll out the update. Twitter uses snowflake IDs for tweets, direct messages, users, lists, and all other objects available over the API.
Discord also uses snowflakes, with their epoch set to the first second of the year 2015.
Instagram uses a modified version of the format, with 41 bits for a timestamp, 13 bits for a shard ID, and 10 bits for a sequence number.