Google used to do that, but then stopped. You can still do it manually by specifying by excluding them in (every) search you do,but the list can get along and

Google used to do that, but then stopped. You can still do it manually by specifying by excluding them in (every) search you do,but the list can get along and it is far from a good user experience. Kagi has this feature built in and it is a good user experience. You can also use the uBlacklist browser plugin. My problem with that is that is slows everything down. I am not certain but I think all the works is done after the search is complete. That it filter the actual result. The two above limit it from ever being part of the result.