If you're looking for a simple and effective way to keep your kitty off the counter, aluminum foil can be a great solution. Just lay a sheet of foil across the areas you want to protect, and most cats will avoid walking or jumping on it. Some may be deterred by the noise the foil makes when they touch it, while others may not like the feel of it on their paws.
Of course, there are always exceptions to the rule. Some curious kitties may be intrigued enough by the aluminum foil to investigate further, in which case you may need to try another method of keeping them off counters (or just keep a closer eye on them). But for many cat owners, using aluminum foil is an easy and inexpensive way to keep their furry friend from getting up where they shouldn't be.