Traffic source

A traffic source is the "buy side" of arbitrage: wherever the operator gets its visitors. The common ones are social platforms (paid social), content recommendation networks (native advertising), search engines, and lower-cost channels such as push notification traffic and pop traffic. Visitors who arrive without being paid for are organic traffic.

Sources differ in price, volume and intent. A click from a search ad is expensive, yet the person was already looking for something. A click from a social feed is cheaper, but the person was scrolling for entertainment and needs a stronger reason to care.

The traffic source also matters to the feed. Search engines decide which sources their partners may use, a process called traffic source approval, and some channels are widely refused because of their history with invalid traffic. Under Google's rules for Related Search on Content, any ad or link on a source under the publisher's control must describe the destination page accurately. Naming conventions such as Native-to-search and Social-to-search simply state the source first and the monetisation second.

Think of it like this

If your page is a shop, the traffic source is the road the customers came down: a busy high street, a quiet lane or a motorway exit each bring a different crowd.