Gmail offers a great search feature similar to Google search. It is very easy to use.
If you are searching for emails that are only in Inbox and if you do not want to include the emails from your sent item or from spam folder or from any labels use the following method to do this search.
Type in:inbox
in:spam
in:sent mail
in:trash
This operators only searches inside a specific folders instead of all emails in your Gmail.
You can use advanced search operators like
From:
To:
OR
And
Subject:
You need to use these operators next to the in:inbox or next to any folders that you want to search.
If you have any questions or suggestions, please post a comment.