Conversation threading is a feature used by many email clients, , , and in which the software aids the user by visually grouping messages with their replies. These groups are called a conversation, topic thread, or simply a thread. A discussion forum, e-mail client or news client is said to have a "conversation view", "threaded topics" or a "threaded mode" if messages can be grouped in this manner.
Flat, or flatness, describes an object or condition that is very smooth or level.In Great Britain, Ireland and Australia, as well as in English spoken in Commonwealth countries such as India, a "flat" means an apartment.