This website is designed to instruct visitors about the meaning of words and their correct usage. To instruct is to give instructions, to teach.
Teachers are often called instructors because their job is to instruct, to give knowledge or instructions. The subtle difference between "teach" and instruct is that you can teach almost anything: concepts, ideas, theories or, say, history. When you instruct someone, you're giving them a set of tools or tasks to do something specific. That's why furniture, toys, and model rocket kits come with instructions: they instruct you how to assemble them.