The above are two good, and siilar in approach answers, but there are two issues it seems no one includes:
1) If you house was built before 1978 it must be inspected by a certified contractor or lead ... read more
We like to use a sanded caulk that matches the grout for that seam between the countertop and backsplash. The flexibility of the caulk allows it to expand and contract without cracking out like normal ... read more