A teacup plate is a plate where you rest your teacup. I believe the term 'saucer' is used in the UK, to described these tea ware. Saucers are normally circular in shape and may have a depression in the middle of the plate to prevent the teacup from sliding around on the saucer.
Call it anyway you want - plate, saucer, tray, coaster, holder or dish. The 1st two pix shows some of the teacup plates in my collection. You will observed that even a gaiwan (literally means covered bowl) comes with a plate. And….such plates need not be circular in shape. The wooden rectangular teacup tray in the 1st pix is made from vietnamese teak. The 3rd pix shows Lau Yu Fat teashop in Hong Kong, where I had a sampling session with Mr Lau. Notice the square wooden teacup holder that came with my teacup. If you google Japanese tea ware, teacup plates can be very pretty and well decorated. Some of these Japanese plates are made from copper or tin.
Why use a teacup plate? It helps keep the table dry. Some teacups may have a rough base and using a teacup holder may prevent scratches to the table top. To me, the indirect advantage is that it gives the tea drinker a sense of personal space. If you have a tea session with 3-4 friends, using a teacup plate would help the tea drinker know where to place his teacup after drinking…..not to his left or right but on the teacup plate. For a bigger tea session with 5 friends or more, and if you use similar cups, having teacup trays may help the tea drinker drink from his right cup.
There are tea sets that does not come with teacup plates. The last pix shows a new goldfish theme tea set that does not have teacup plates. When I brew tea myself, I do not use teacup holders for my teacups.
Using teacup plates in a Chinese tea session have its usefulness and help enhance the ambience of drinking Chinese tea. Do you use a teacup holder?