It's easy to see why recessed lighting is so popular. Flip a switch, and fixtures tucked into the ceiling bathe a room in a warm glow. Flip it off, and those same fixtures seem to disappear—no lamp shades to dust, cords to hide, or chandeliers to block the view.
Installation is fairly simple, especially in new construction. The metal housing, or can, has a bracket that gets nailed or screwed right into the joists, before the ceiling is drywalled. (Wiring should be done by an electrician.)
But this isn't practical for remodeling jobs if you have to demolish a ceiling to access the joists. So manufacturers make special retrofit units that require only a small opening. You simply cut the correct-size hole into the drywall (a drill-mounted hole saw works better than a jigsaw for this job) and then insert the fixture. In new or existing construction, ceilings containing insulation require special heatproof fixtures.
If your home has older recessed lights and you want to update with new low-voltage models, you can buy retrofit kits with self-contained transformers to convert house current into the necessary 12-volt power source. All the major recessed light manufacturers sell such kits (check a lighting showroom or the Internet), which run about $75 per fixture.