How to show unread messages or emails in Gmail

I was trying to filter and only retrieve the unread email in my Gmail. This suppose to be relatively simple and straight forward feature for email service provider. However there wasn't any 'show only unread email' button or link. Later I found out you can actually go to the email search box and type 'Is:Unread' or 'Label:Unread' (without quotes). Then it will just filter all the unread email and messages in the search result. Simple, easy, straight forward.

Now I can go through my unread email months ago...