The electrochemical process of anodizing transforms aluminum into a nonreactive, scratch- and stick–resistant surface. You don't have to worry about metal utensils scraping this surface, as you would with a nonstick pan.
How to identify: Hard-anodized aluminum cookware looks as if it belongs in a restaurant kitchen―it's matte gray, industrial, and extremely attractive.
When to use: Use it the same way you'd use a nonstick. Hard-anodized aluminum does it all (and has a high price tag to match). Although it will sear a tuna steak or a pork chop beautifully, its surface is chemically treated to be "low stick," and it releases delicate foods easily.
When not to use: When you have a lot of dishes to clean. The biggest and only drawback of hard-anodized cookware is that it can't go in the dishwasher.
How to clean: With its dull, easy-release surface, it cleans up like a nonstick pan: Hand wash with hot, soapy water and a nonabrasive sponge.