A bay window is a window space projecting outward from the main walls of a building and forming a bay in a room, either square or polygonal in plan. While most bay windows protrude from a building, some bay windows are level with the exterior and are built into the interior of a room. The angles most commonly used on the inside corners of the bay are 90, 135 and 150 degrees. Bay windows are often associated with Victorian architecture and were a part of the Gothic Revival style. They first achieved widespread popularity in the 1870s.

The windows are commonly used to provide the illusion of a larger room. They are used to increase the flow of natural light into a building as well as provide views of the outside that would be unavailable with an ordinary window.

The interior of a multi-story bay window in Chicago, Illinois

Two superposed Renaissance bay windows in Colmar, France

Bay windows at Augustinergasse in Zürich

Typical bay window for a residence

A bay window in Turl Street belonging to Exeter College, Oxford.

Robert Joseph "Bob" Vila (b. June 20, 1946) is an American home improvement television show host known for This Old House (1979–1989), Bob Vila's Home Again (1990–2005), and Bob Vila (2005–2007).

Vila, a Cuban American native of Miami, Florida, received a Bachelor degree in entomology from the University of Florida in 1969. After graduating, he served as a volunteer in the Peace Corps, working in Panama from 1971 to 1973.

Vila was hired as the host of This Old House in 1979 after receiving the "Heritage House of 1978" award by Better Homes and Gardens, for his restoration of a Victorian Italianate house in Newton, Massachusetts. On This Old House, Vila appeared with carpenter Norm Abram as they, and others, renovated houses. In 1989 he left the show under controversial circumstances. Some cite the reason as being a series of conflicts with This Old House executive producer Russell Morash arising from his involvement with outside commercial endorsements, while others cite a specific instance- Vila's commercial work for New Jersey-based Rickel and the subsequent retaliatory pulling of underwriting from Rickel's competitor Home Depot and lumber supplier Weyerhaeuser- as the reason behind his departure. He was replaced by Steve Thomas.