A tent without walls is also known as a “fly.” Here the term fly refers to the outer layer of a tent or the piece of material that is tied up using a rope. These are the minimalist and standalone shelters. At times purpose-made standalone flies are also referred to as bivvies, bivouacs, hootchies or tarpaulins. These tents are normally used for keeping moisture like rain or condensation of the sun off the guest. At other times we can see them in use as groundsheets.