Advertising is a form of commercial propaganda that aims to extract capital by means of psychological influence. It is relevant to digital privacy because it commonly appears in software as a type of anti-feature, because network-enabled advertising is a common vector for malware, and because advertising is one of the primary driving forces behind surveillance capitalism.1
A certain amount of advertising can be stopped at the network level by a DNS-based ad blocker such as Pi-hole installed on hardware connected to your local network. DNS-based ad blocking has the advantage of working across all devices connected to your network, including those that don’t support blocking on-device. This type of ad blocking has limitations, though, in that it cannot afford the same level of granularity of an in-browser ad blocker and does not work with devices or applications that do not respect network-level DNS settings, such as those that utilize DNS-over-HTTPS.
Browser-based ad blocking provides a finer-grained level of control and can be highly effective, but of course is limited to blocking ads in the web browser. It should be noted that ad blocking extensions can weaken anti-fingerprinting techniques that preserve strong anonymity through uniformity among user agents, such as those employed by Tor Browser. In other cases, the privacy advantages far outweigh the disadvantages, and using an ad-blocking browser extensions should be a fundamental part of maintaining one’s digital hygiene. uBlock Origin represents the state of the art of ad blocking across major browsers.