Marking strings as fuzzy can be useful in more than one instance during the software localization process. The Fuzzy flag, generally used to signal that a translation needs revision, has its most typical use cases described below.
Marking as fuzzy in a Language page
Next to each translation in any Language page, there is an F button to Toggle a Fuzzy Translation. Hit it if you want to let other people know that the translation requires reviewing. This can be very useful in the process of proofreading translations.
You can also mark translations as fuzzy in bulk in the language page. To do this, check the boxes next to the terms whose translations you want to mark as fuzzy, and choose in the select menu at the bottom of the page the option to Toggle Fuzzy.
Marking as fuzzy in View or Add Terms
If an owner or an administrator edits a term, marking the translations in all the languages as Fuzzy is a good idea, because this will allow them to notify the contributors to check the Fuzzy translations if they are still correct after the change.
Marking as fuzzy on Import
On import, project owners and administrators have the option to overwrite the old translations in the language where they are updating the strings. If they choose to overwrite the old translations, they can also mark all the other translations in the other languages as Fuzzy for that term. This is particularly useful when updating translations in labels-based projects.