Countertops are normally secured to the cabinet frames with silicone caulk. Usually, fabricators must make at least one seam on site. But they've developed clamping tools and gluing techniques to create joints that virtually disappear after the excess glue is sanded down. Like solid surface materials, granite stone is cut and polished off-site, including cut outs for sink openings. That demands a lot of accuracy and coordination to make sure measurements and templates are correct.
Granite is secured to the cabinets with silicone caulk, but one major difference is how it's seamed.
With granite, the joints don't totally disappear, but in a sense, that's what separates natural stone from manufactured products. You can install backsplashes after the countertop is secured, especially if you've ordered granite or solid surface which can't really be scribed to fit flush with an imperfect wall. A ceramic tile backsplash, for example, can effectively hide any gaps there and keep water from dribbling down the wall. And a backsplash doesn't require a special backerboard so you can apply the tiles directly to the drywall. For laminate countertops, a piece of matching laminate is sometimes secured to the wall and caulked at the seam to repel moisture.