Well, lets face it. Bad things happen. Either you neglect a tooth decay and now it is too late to save the tooth or for any other reason you have a broken tooth which is not savable, you may need the tooth out.
Extraction of a tooth is done by moving the tooth to the sides to push the bone around it back and get it loose before taking that out. It is very similar to trying to pull a screw out of wall or piece of wood without unscrewing it. Of course it is not as easy as that because here we are dealing with human body and not a wall. And there are lots of techniques involved to make that safer and easier for the patient.
In some cases if there is not much left from tooth to hang on to or bone is very hard and does not let the tooth move then we may need to do a surgical extraction. This means we need to open the gum around the tooth a bit and remove some of bone around the tooth to make it possible to push the tooth out of its socket.
Picture below shows a “dry Socket” after extraction. It happens if for any reason blood clot comes out of the socket. Blood clot is necessary for healing process of the wound. If blood clot comes out, bone will remain exposed to air, saliva and food, will get contaminated with bacteria and does not heal. This cause a lot of pain which some times is not controllable even with painkillers. Usually treatment would be cleaning the socket, disinfecting that with special medication and prescribing antibiotic to patient.