Did you even loose track of some your unread mail in your Gmail Account?
For some reason Google does not provide a visible button to filter or find unread mail in your mail box. In the desktop browser it can be done from the advanced search dropdown. However, in the mobile apps, e.g. on your iPhone or iPad there is no advanced search. But, you can still use the direct advanced search syntax to find your unread lost between the dozens of mails that you receive.
Unread mail does in fact have the label “unread” attached – though not visible besides the bold text. Therefore it possible to do a label search on the unread mail.
If you want to search unread mail within one of your ordinary label, or e.g. only you inbox, simply combine the label search with another one:
Another search syntax that also do the trick is:
Another tip is to bookmark the search result page on your mobile device, that way your will always have easy access to your new – and old – unread mail.