Tired of popups constantly asking you to enable cookies or pop-ups asking you to sign up for a newsletter? A free and open source extension for Safari called Hush means you'll never see them, along with nags for things like enabling notifications. It's the kind of thing you install and then forget about until you use someone else's computer or phone, then wonder how anyone lives without it.
Hush isn't an ad blocker, though it does use the same Safari features utilized by ad blockers. Joel Arvidsson, who created and maintains the tool, states that it has "absolutely no access to your browser habits or passwords" and that it doesn't track behavior.
After installing Hush, you will need to ensure that the extension is enabled in Safari. On a Mac, you can do this by opening Safari, opening Safari's settings, and heading to the Extensions tab. Make sure that "Hush" is checked. On an iPhone or iPad you'll need to open the Settings application, scroll and open Safari, then scroll to an open Extensions. Ensure that Hush is set to on.
After that, you're done—Hush will run in the background and block various annoyances. The entire application is half a megabyte, meaning it won't have a significant impact on your system performance.
What it does have an impact on is your browsing. All of us are sick of prompts for enabling cookies and will be glad to simply not see them. Now, this doesn't mean that you're blocking all cookies—that would break a lot of websites. Legally, according to the European Union regulation known as GDPR, websites have to ask permission for any "non-essential" cookies. Not every website complies with that law, though, in part because it only applies in Europe and in part because some people disobey the law. Hush simply stops you from every seeing the cookie pop-up, which means you can browse the web without that particular interruption. It also means that you never give consent to non-essential cookies, which probably on balance is good for your privacy even if it doesn't force anything.