You are probably looking for information on one of the following:
Rain Gutters - These are the long troughs hanging under your roof's eaves. Their intention is to catch roof rain run-off and send it down downspouts (the kind the Itsy-Bitsy Spider climbs up). They are substantially less effective when full of leaves, because the leaves act as a sieve and sponge, absorbing the water. Maintenance of gutters qualifies as Home Improvement & Repair if you need a professional to clean them or do other work with them.
Street Gutters - The edge of the street between road and curb. Their intention is to guide water down the street so it can flow into storm drains. They are substantially less effective when full of leaves. In Davis, we have curbside leaf pickup, so when it's rainy, please move your leaf pile 6-9" towards the street so the water can pass by unimpeded. A rake is an excellent tool for this task.
From the Latin, gutta means "a drop" and in this linguistic sense refers to the channel form and flowing function.