Bi-fold doors are the doors that fold in on themselves; whether they come in two or four sections (or more, if they're custom-made), the opening is in the middle. They are usually suspended from overhead tracks by rollers or casters, with lower tracks to guide them. The panels, connected by centralized hinges, can be pulled back and forth by a knob or pull on the innermost panel.Most often used as an alternative to sliding doors, French doors, and regular closet doors, larger ones can be used as room dividers, while their smaller versions can be found in kitchen pass-throughs or laundry rooms.The benefits of saving a lot of space are obvious: they take up much less space when opened than regular doors; it can be argued that installing bi-fold doors actually creates extra space. For example, when used as patio doors, bi-fold doors allow you to open up your house outdoors, and let the fresh air and natural light in. That makes them ideal wherever the unobstructed views are desirable.Bi-fold doors look equally good whether they're closed, open, or half open. You can choose from a range of materials: wood, aluminum and vinyl are the most common. Bi-fold doors made from premium hardwood, like timber, can add a touch of class with a modern flare to any space.Are there some drawbacks to installing bi-fold doors? Although more common than before, they are still considered somewhat of a luxury: they cost more than regular doors. The cost may be well worth it, though: not only because of their high functionality, but because they tend to give any space a contemporary, elegant appearance.What about the security? Don't get fooled by their looks: they are made to be robust, and can be additionally fitted with anti-drill key cylinders and high-security hinges. If you're worried about children trapping their fingers between the panels, you'll be relieved to find out that the newest bi-fold doors come with a safety feature to prevent such accidents.People who habitually pull the knob on a bi-fold door outwards, like on a regular door - and not sideways, like they are designed to be pulled - can put a lot of pressure on the tracks and casters. That can lead to tracks becoming bent, or casters slipping out. If you decide to install bi-fold doors, to enjoy all the benefits that they have to offer for a long time, make a point to always push the doors to the side in a linear fashion.