Baking mats are non-stick floppy “plastic” sheets that you put on top of a baking tray before baking, instead of greasing the tray or lining it with a cooking paper. They prevent the food item being baked from sticking to the pan.
There are various makes and brands, which can be made of food-grade silicone or Teflon.
The baking mats are reusable. You simply wash them after using them, and roll them up for storage between uses.
A baking mat won’t last for ever, but it will last for a very long time.
They are ideal for baking anything that generally melts, spreads out and then usually sticks to cookie sheets, such as cookies. They also help heat distribution for more even browning of the baked goods on top of it. Some say, though, that bottoms of cookies baked on them don’t brown up as nicely as they would otherwise, and that baking time required may increase.
They can also be used for non-oven purposes: they can be used as a “rolling board” on the counter to roll out pastry dough or pizza dough on, and they can be used as a non-stick “plate” when you are making candies, such as dipped chocolates, caramels, toffee apples or popcorn balls.
You can cut or trim them with scissors to fit whatever size pan you want.
Many manufacturers say their silicone mats are top-rack dishwasher safe. Stubborn stuck-on food can usually be easily released with soaking. Some people advise that to remove stains, you can try a combination of lemon juice and sunlight.