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The word 'towel' is used to describe the material you dry yourself off with after swimming or showering.
Using an adjective in front of the word towel can pinpoint its specific function.
For example:
Bath towel - for use after a bath or shower
Swimming towel - for use after swimming in a pool
Hand towel - for use after washing your hands in the bathroom (usually a smaller towel)

Swimming towels are relatively cheaper than bath towel They are usually used after swimming or at he beach. Bath towels are smaller than swimming towel.They are used mostly after taking a shower/bath.
Example sentences:
Can you please bring my bath towel? I am almost done with my shower.
Don't forget to carry your swimming towel today.

▪ Bath towel
This is a large towel that you use to wipe your body after a bath or shower.

▪ Beach towel
This is and extra large towel used at the beach to lay on and to dry yourself after a swim in the ocean.

▪ Hand towel
This is a small towel used to dry your hands after you washed them.

A towel or bath towel is what we use to dry ourselves after a bath or shower. If you also have a smaller towel just for drying your hands, then this is a hand towel.
"The bath towels are in the airing cupboard."

A large towel used to dry off your body after a bath or a shower is called either a bath towel or a bath sheet. Generally a bath sheet is the larger of the two.

"Beach towel" these are the only "large" towels that exist. They are larger than your bath towels. Although not used to dry yourself it can be used for that purpose.

"Bath towel" this is the most common towel to "dry yourself". Usually people take these towels to pools or the beach and use them at home.

A bath towel is what you dry yourself with after having a bath or a shower.
A beach towel is what you dry yourself with after you go swimming at the beach or a pool.
A bath sheet is the same as a bath towel but bigger.

A bath sheet is a very large towel. You can also call this a bath towel.

The most common term is "bath towel". If you are using a towel specifically designed for the beach or swimming pool, this is called a "beach towel". In some areas of England they also refer to a large towel such as this as a "bath sheet".