Teapots are like pottery with a handle a spout and a lid that usually holds boiling water and tea leaves in them to extract/soften the flavour and serve to people.
The first time a teapot was used was during the late Yuan Dynasty, when an ewer like vessel was first used. (ewer is like a tall and skinny teapot with no lid) This was the first time they had done tea preparation like this before.
Images from Wikipedia