Canvassing is the systematic initiation of direct contact with individuals, commonly used during political campaigns. Canvassing can be done for many reasons: political campaigning, grassroots fundraising, community awareness, membership drives, and more. Campaigners knock on doors to contact people personally. Canvassing is used by political parties and issue groups to identify supporters, persuade the undecided, and add voters to the voters list through voter registration, and it is central to get out the vote operations. It is the core element of what political campaigns call the ground game or field.

Organized political canvassing became a central tool of contested election campaigns in Britain, and has remained a core practice performed by thousands of volunteers at each election there, and in many countries with similar political systems.

Canvassing can also refer to a neighborhood canvass performed by law enforcement in the course of an investigation. This is a systematic approach to interviewing residents, merchants, and others who are in the immediate vicinity of a crime and may have useful information.

In the United States, the compilation of election returns and validation of the outcome that forms the basis of the official results is also called canvassing.