A big part of being a gourmet cook is knowing which tool best suits which purpose . . . and having that tool at hand. This definitely goes for food strainers, as using the wrong one is hardly better than using none at all. Trust me.
Chinois and China Cap
Both of these are cone-shaped metal strainers. They are used for straining stocks and sauces. The chinois is made from a very fine mesh screen and is useful for consomme. The china cap has a perforated metal body and can be used with a pestle to puree soft foods.
I recommend this Chinois Set. I use mine for everything from stocks to puddings . . .
Skimmer and Spider
Both of these have a long handle and are used to remove fat or impurities from liquids. The skimmer has a flat disk used for skimming stocks or removing foods from soups or stocks. The spider has a finer mesh disk and is used to remove items from hot fat.
I use this spider for fishing out all fried foods. It works great!
Cheesecloth is a woven cotton gauze used for straining stocks and sauces and wrapping poultry or fish for poaching. Always rinse cheesecloth before use; this removes lint and prevents it from absorbing other liquids.
I always have lots of cheesecloth on hand for multi-purpose uses . . .
A food mill strains and purees food at the same time. Food is placed in the hopper and a hand-crank turns the blade forcing food through the disk.
Food Mills are wonderful for anything you want to puree, (tomatoes, potatoes, apples, etc.) I also want to recommend a potato ricer. I use this a lot for potatoes, but I also love it for squeezing juices out of frozen chopped broccoli and spinach . . .
A sifter is used for blending and removing impurities from dry ingredients such as flour, cocoa, and leavening agents.
As with the other categories of kitchen tools and implements, having the right food strainer for the job is a big plus. I have everything on this page and more, and I encourage you to do the same.