Technically, a soffit is the underside of any element of a building. The most common soffit is found in the area under the eaves on the exterior of the house. The soffit extends from the side of the house to the edge of the eave and closes the space beneath the eave.
The soffit is more vulnerable to weather damage than any other part of the house. Wet material rots, and a soffit can be repeatedly soaked by water from torn shingles, damaged or rusted flashing, ice dams, or poorly functioning gutters.
Squirrels and birds can also damage a soffit, since they like to nest in the space in the space behind soffits if they can find a point of entry. Bees, hornets, and wasps do not actually damage a soffit, but when they build a nest behind a soffit, they present a problem for the homeowners.