All gutters are either sectional or seamless (or continuous). Sectional gutters are sold in pieces and installed as component systems. All do-it-yourself gutter systems are sectional, though pros install these, too.

The sections themselves can be over 20 ft. long each or cut to any size with a hacksaw. Snap-in-place connectors join gutter sections to each other and to downspouts. All sectional systems have end caps, corner pieces and drop outlets for connecting to downspouts.

The drawback to sectional systems is that all those seams can eventually invite leaks. Seamless gutters won't leak at seams because there are none; sections join only at inside and outside corners and at downspout outlets. That's why they're the most popular configuration.

Seamless gutters, made of aluminum, galvanized steel or copper, are extruded to custom lengths on site using a portable machine.