Although often considered only as an afterthought, closet doors are just as important as the shelves, hanger rods, and other accessories inside your reach-in closets. The most common types of doors are swing doors, sliding doors, and bifold doors, each of which has its advantages as well as disadvantages.
For small closets with widths of about 20 inches or less, a single swing door may suffice. Beyond this, two doors that are hinged on opposite sides of the closet (French doors) may be necessary, as a single door would require a huge space in which to swing open. Two doors may be good enough for closets less than 36 inches wide, but for those that are wider, the two swing doors will have to be wider than at least 18 inches, which would then require a large space in front of the closet.
Thus, if your closet is three feet or wider, your choices for its door are limited to either a sliding or bifold door. Both these types do not require a large space fronting the closet. The sliding doors do not even protrude out of the closet at all. Bifolds, on the other hand, do need some space in front of the closet because they open outward. The space, however, need not be as wide as half the width of your closet, as they fold unto themselves when opened.
Sliding doors are almost always made of two door panels, with one sliding in front or behind the other. The only exceptions are those that slide inside the wall, but this is not very common. This means that you will never be able to fully open the closet, as half of it is always concealed.
With bifold doors, you have the advantage of opening the entire closet at one time without the need of an excessive amount of space for the doors. With the use of tracks, which may be fastened to the top or bottom of the door, or even both, opening the door is smooth.
One drawback of bifold doors, compared to swing doors at least, is that you cannot use their backs for small shelves for additional storage, or hooks for belts, ties, or similar accessories because the doors fold into each other.