Looking at the options for blocking ads, people usually first look at browser extensions. Google's plan is to disable adblock extensions in 2024. The alternative is usually an app (on phones) or a "VPN" that does filtering for you. All these methods are quite heavyweight, and require installing software on your phone or PC. What is less known, is that you can you DNS-over-TLS or DNS-over-HTTPS for ad blocking.
What is DNS-over-TLS and DNS-over-HTTPS
Since Android 9, Google has provided a setting calledPrivate DNS. Traditional DNS is unencrypted UDP so anyone can monitor your requests and/or return false records. With private DNS, DNS-over-TLS or DNS-over-HTTPS is used to guarantee the DNS request is sent to the server you configured. Which Google hopes is of course Google's own public servers. If you do so, your ISP and hotspot providers no longer can monitor, monetize and enshittify your DNS requests - only Google can do so.
Subverting private DNS for ad blocking
This is where AdGuard DNS comes useful. By setting the AdGuard DNS server as your "private DNS" server following the instructions,you can start blocking right away. Note, on PC you can also configure the Adguard DNS server on the Browser settings (Firefox -> Enable secure DNS and Chrome -> Use Secure DNS) instead of configuring a system-wide DNS server. Blocking via DNS, of course, limits effectiveness to ads distributed from 3rd party servers.
Other uses for AdGuard DNS
If you register for Adguard DNS, you get your "own", customizable DNS server address to point to. You can, for example, create your own /etc/hosts style records that are now available to all you devices you have connected to the Adguard DNS server - whether your a are home or not. Of course, you choose to use the personal DNS server, your DNS query privacy is in the hands of AdGuard.
Going further
What else is ruining the web than Ads? Well commercial social media. An article ("Ei näin! – Algoritmiähky") from the latest Finnish Magazine SKROLLI (mainos: jos luet suomeksi, Tilaa skrolli!) hit a chord for me. The algorithms of social media sites are designed not to serve you, but to addict you. For example, If you stop to watch a hateful meme image, the algorithm will record "The user spent time watching this, show more of the same!". It doesn't help block or mute - yeah that spefic hate engager will be blocked, but all the dozens similar hate pages will still be shown to you. Worse, the social media sites are being overrun by AI-generated crap. Unfortunately the addictive nature of the algorithms works. You reload in vain, hoping this time the algorithmic god will show something your friends share. How do you cure addiction? By blocking yourself out: 
Epilogue
I didn't block myself out of Fediverse - yet. It's not engineered to be addictive, which is also probably why it isn't as popular as the commercial alternatives...
