Firstly, there are eight basic types of window.

Box sash windows are common in period homes. The windows are divided vertically in two and are corded. Either both windows (top and bottom) can run along the cord and be opened, or sometimes just the bottom half can be opened. Sash windows which allow the top window to be pulled down are useful in a family home as the top window can be opened to let in fresh air with no risk of small children climbing out.

Slider windows open by allowing the window to slide to the right or left. These are a more modern feature - sometimes used as glass door panels, opening out onto a patio or garden.

Casement windows are hinged and swing open either from the side or from the top. Modern versions, often made from UPVC can have the option of opening both ways. These windows also have a mechanism so that you can fix the width of the opening on any given occasion.

A fixed panel is a window which can never be opened. These are sometimes fixed into front or back doors or where ventilation is not needed. Sometimes these windows are made from stained glass or in an unusual shape for added aesthetic interest.

Bay windows protrude out from the wall and look attractive both from the outside, breaking up the flat appearance of the outside of the building, and from the inside where they provide a bit of extra space and a defined setting for a seat or other piece of furniture.

A French window is a glazed panel door, allowing access usually to the garden or a balcony.

An oriel window is a bit like a bay in that it projects out from the wall of the building, often on an upper floor.

Finally a velux window is one that is fitted into a roof to allow light into an attic or loft conversion. Alternatively a dormer window can be fitted, which protrudes out from the roof, parallel to the walls beneath.

Once you've worked out the different styles of window, the next task is to decide on the type of window frame and glass you want. Window frame materials are generally wood (soft or hardwood), UPVC, aluminium or steel. Wood is most in keeping with period houses although the frames are now thicker, to accommodate double glazing. Hardwood is the most long lasting type and a good window fitter should guarantee the paintwork on a timber frame for several years so maintenance won't be an annual chore.

UPVC frames look out of character in a Victorian or Georgian home and can't incorporate the necessary detailing of an original frame. But in a more modern home they are virtually maintenance free and better than wood for draft and heat loss prevention.

Metal frames can be slender and stylish in a modern home and can be made in all sorts of interesting shapes.

Next comes glazing. All new homes and replacement glazing now has to be double glazed. This helps with security and cutting down on noise pollution and draft and heat loss prevention. For added security consider toughened glass, laminated glass or wired glass (which can look rather industrial). If you have a fixed panel then stained glass is a decorative option. You'll usually need to involve a specialist if you want something custom made to fit a particular window frame or door panel. A modern or traditional design can be incorporated.

If security or aesthetics aren't an issue then ordinary sheet glass can be used which is relatively cheap but can include distortions. Alternatively float glass is also relatively cheap and does not contain distortions. However it can only be used above waist height as it doesn't meet Building Regulations.

With the right style of window, a suitable window frame material and an appropriate type of glass windows can revitalise a building and define its look.