While some GMail users download email locally to Outlook or Thunderbird and then use Windows desktop search to find emails, GMail itself offers some very powerful search capabilities. Let's explore the most useful Gmail search filters and their usage:

Q: I have hundreds of unread emails in my Gmail Inbox but not all of them show up on the main page. Can I bring up view in GMail containing only unread messages.
A: label:inbox is:unread

Q: My boss sent me a PDF document last month that I can no longer locate in the Inbox. Can you help me find it.
A: from:Name_Of_Boss filename:pdf after:2007/07/01 [yyyy/mm/dd]

Q: I received an email from Paypal support last week. I am not sure if I deleted the message, archived it or marked it as Spam.
A: from:Paypal in:anywhere

Q: I have dozens of unread email messages in the Inbox but I am in a hurry to check them all. Show me just the messages that are for me.
A: is:unread after:2007/09/03 to:your.email@address.com

Q: Ryan is a good friend who send me pretty interesting PowerPoint / Word files that often have inspirational quotes, beautiful natural landscapes and funny slide shows of Cats. I love it all but they take too much space.
A: from:Ryan has:attachment [Select all and then delete]

Q. I accidentally deleted an important email message from a colleague. My GMail trash is already overflowing. How do I retrieve that particular message.
A: label:trash Name_Of_Your_Colleague

Q: I use GMail to automatically backup my WordPress blog. The database backup are stored via email attachments as Zips. Since I am running short on GMail storage, I would like to delete all backups that are older than two weeks.
A: filename:.zip before:2007/08/15 wordpress

Q: While chatting over Google Talk, Veronica sent me a link to her Flickr pictures.
A: in:chat from:veronica flickr.com

Q: Show me all emails from my Boss that he marked Urgent or Important in the subject.
A: from:Boss_Name subject:(Urgent OR Important)

Q. I have two contacts in GMail with similar names - Peter King and Peter King Junior. Can I see emails the received from the former contact.
A: from:Peter King -Junior

Search Shortcuts: Instead of typing label:unread, you can simply type l:^u

Important: Unlike Google web search, GMail won't suggest search results that contain plurals or misspellings of your search query. For instance, a search for "computer" will only show email with that exact word - you won't see messages containing the word "computers".