Minecraft wiki entry for Version_formats, associated text: After the full release of Minecraft, public development versions called "snapshots" have been published most weeks showing the development of that version at the time. Snapshots use a very different format to other releases: the format is the two-digit year, followed by the letter "w", the two-digit week of the year, and then a revision letter for the amount of snapshots released in that week. For example, 18w10d was the fourth snapshot ("d") released in the 10th week of 2018.