Servers, also known as teapots. Teapots can be used to serve tea (as the titles say) and also prepare and steep the tea. The teapots usually have handles, a large body to hold the tea, a spout, and an opening at the top where the lid can be placed. The lid is removed while putting tea bags or tea leaves within the body, so the steeping process can occur.
Other teapots possibly have a built-in strainer at the tip of the spout, as with steeping tea leaves, you wouldn't want leaves inside of the tea, unless you prefer it that way. And other teapots that don't have a built-in strainer have to be strained manually, by using a tea strainer to strain the tea without letting the tea leaves fall.
Normally, there is always a small hole in the lid of a teapot, so the heat won't be trapped and the spout won't drip.
A tea cosy can also be used in enhancing the steeping process.
The Wikipedia page on teapots is .