String instruments have two main parts, a short fat body, and a long thin neck. Those two parts need to be joined. Spanish guitar makers manage to build the two as one piece, without a joint, but only because of certain aspects of that style of guitar and the working arrangements of the makers. Violin makers do not attempt to make the two components as one, and use a very simple tenon joint, which Stradivari sometimes reinforced with a nail.
Neither of those joints is accurate or strong enough for a modern steel string guitar. For many years, a tapered dovetail joint has been used, but has been replaced more and more by a simple bolted joint that allows infinite adjustments during manufacture and easy removal for future repairs.
From a tonal point of view, there will be continual arguments over the advantage or disadvantage of any form of neck joint. I do love working on dovetails, but my own experience and training tells me that, if there is any difference at all, a joint that is tightly connected with maximum wood to wood contact is likely to give the best results. Most dovetails offer very little wood to wood contact (my own estimate is 13%). With a bolt on neck, wood contact can be 100%, plus all the other advantages. Hopefully I will be able to say more when time permits.