What is "formatting"?
Wikipedia describes this term as follows:
Disk formatting is the process of preparing a data storage device such as a hard disk drive, solid-state drive, floppy disk or USB flash drive for initial use.
On Android, in most cases this refers to external SDCards, where even on non-rooted devices the user has the possibility to format the "storage device" (the corresponding item can be found in Settings→Storage). Advanced (and rooted) users might even format other partitions in internal storage, and Custom Recoveries (see: recovery-mode) usually provide corresponding options.
So if you have issues with this kind of formatting, this tag is fitting for your question.
What this tag is NOT about
- file-system: as formatting creates the structures, which are called "file systems", this obviously is a related tag which already is implied with the term formatting. Reasons to additionally include it might be troubles formatting specific file systems, concerning compatibility or errors occuring only when using those systems.
- file-management: this is the step following after you created a file system. Obviously the latter is a pre-condition to the former :)