Traffic Source: Google Analytics

There are three types of traffic sources.

1. Search Traffic- This is the traffic of users who land on your website or blogger via some search on any Search Engine. That is, if a user searches for any content on a search engine and the result is shown for that particular search has your address in it and the user click it to reach to you. If you have Google Analytics or any other analytic service integrated to your site or blog. Then try adding up the visits for keywords, they'll be equal to visits in search Traffic area like above it is 6 visits.
2. Referral Traffic-  This simply means when users reach to a web address by clicking on the link from some other sites. Well if you have a blog then you need to promote using free services. Just writing won't let good amount of traffic directed to your address, especially if you are a beginner.
3. Direct Traffic- When users reach your spot by sources other than the above two. Basically that is when your web address is directly typed into the address bar or when your link is clicked in any offline document or other offline sources. You might be knowing this that when a linked is clicked in any document it is directly added to the address bar of your default browser. And that will interpreted as putting web address directly into address bar.

There is a fourth category too, called Campaign. This shows traffic received via paid Google ads.