Most people will tell you there are two types of traffic, free and paid. While I agree on the number, I disagree on the types of traffic. First of all, nothing is free. “Free” traffic costs you time. And anything that costs time can be outsourced to someone else, thus making “free” traffic cost you money.
I see the two categories as organic and advertisement. Now it might look like organic traffic is just another word for “free” but there are some important differences. And as stated, you can pay people to get you organic traffic.
Organic traffic is characterized by people finding links to your website while searching for information on the Internet. Whether they are using a search engine, YouTube, an article directory, or browsing Facebook, they come across information you provide that makes them go to your website for more information.
Advertisement traffic is characterized by your having an ad put in front of your target audience. This can be pay per click, Facebook ads, solo ads, or even ad swaps. People are shown your ad which encourages them to go to your website for whatever is being advertised.
Organic traffic is typically slower than advertisement. It can take weeks or months to get serious traffic from the organic sources. It generally takes a while to get your website to the top of any search lists. And each source generally has different rules, and these rules change. Advertisement traffic tends to happen immediately. Your ad is placed in front of the readers right away.
However, advertisement traffic is very short term. You only get traffic when the ad is run, and in some cases, a few days after. Organic traffic continues coming for weeks, and even months. For example, I have a comment on a blog post that generates fresh traffic every month. When the owner of the blog promotes their post again, my comment is seen by more people. And some of them click on the link in the comment.
Some people swear by one type of traffic or another. I feel it is a good mix of both types of traffic that work best. You can pay for advertisements to get immediate traffic, and start getting organic traffic for long term traffic.