Not directly. They’re used to track people’s behavior on your website after seeing an ad for your company, like knowing that people who see a Facebook ad for stamps are 12% more likely to buy them or whatever.

Not at all. Tracking pixels are installed by advertisers so they can understand if advertising on platform A, B, C actually drives business outcomes X, Y, Z. In other words, they're primarily a tool to see whether you're getting value for the ad dollars you're spending.

(Their secondary purpose is to let you show ads to people who already came to your website, i.e.: focusing your ad dollars on people who might actually care about your products and services in the first place)