A home inspection is a visual observation of the dwelling's systems and components to identify accessible and present defects and safety issues. The inspection is not technically exhaustive.
A home inspection is designed to reflect, as accurately as possible, the visible condition of the home at the time of the inspection. Conditions of a home for sale can change radically in only a day or two, so a home inspection is not meant to predict or guarantee what condition a home will be in when the transaction closes. It's not uncommon for conditions to change between the time of the inspection and the closing date.
A "visual" inspection means that a home inspection report is limited to describing conditions in those parts of a home that an inspector can see during the inspection. Details of the house that are permanently hidden behind wall, ceiling, and floor coverings are excluded, but so are parts of the home that were inaccessible during the inspection for other reasons. Some reasons might include the lack of an access point, such as a door or hatch, a locked access point, an occupant's belongings blocking access, or because of dangerous or unsanitary conditions. Suppose an inspector can't see a portion of the home. In that case, the inspector can't assume responsibility for ensuring that a safe and proper condition exists or that systems operate correctly in that hidden space.