If you're referring too "traffic" in terms of network traffic then it is essentially information (Sent through packets) going to and from the sender the receiver (Receiver being the host server when you're communicating with a website). This process is known as traffic because too much is never good and like we know... same thing as in literal traffic.
To promote traffic is rather difficult, it's more of a question of sales and marketing (What are you offering, who gives a shit etc) You have to promote your site where you can who people who actually want/need your product (Target marketing). This is what most people over the internet use to give you advertisements that most likely are beneficial or related to you and your search results.
I'd suggest talking with large communities of people to aid your website in initial traffic and from then on it becomes word of mouth.
Hope that helps!
There's no place like 127.0.0.1
Traffic is a deal or trade in something illegal.