The term 'Kind of Letter' can refer to three different types of letters. The first is a SCARLET letter, which is a letter of shame or disgrace that was historically used in Puritan society. The second is a CHAIN letter, which is a type of letter that is sent out to multiple people and encourages them to send it to others. Finally, a Round Robin letter is a type of letter that is sent out to multiple people and each person adds their own message to the letter before sending it on.