It's crazy to think that a simple gaiwan––the traditional Ming Dynasty tea set consisting of merely a lid, a bowl, and a saucer––is the greatest brewing technology of all time. But it's true. The first time I used a gaiwan, I didn't think too much about what's so special about it.
When using a gaiwan, you'll soon notice that you have much more control over your brewing than when using a teapot. The "gai" itself is the lid, which can be used to strain the leaves when pouring the tea. You can take a moment to appreciate the aroma of the tea by wafting the underside of the lid under your nose. The "wan" is the bowl that holds the tea leaves while brewing. The wide bowl shape allows the tea leaves their full expansion.
With a gaiwan you can perfectly control the strength of a tea's steeping by paying close attention to the brewing duration. You can also precisely control the pouring speed by adjusting the size of the opening with your finger, using the lid as a strainer. Before pouring the tea, you can peek into the bowl at the leaves and the water color in order to judge if the tea is ready to drink.
A gaiwan also makes additional steepings easy––simply add more hot water and repeat the process. It might take a little bit of practice in the beginning, but it's the time-tested technology for preparing tea, and it really works. Try it out for yourself––once you've learned how to handle a gaiwan, you'll never go back.