The preaching work of Jehovah's Witnesses is done in a very organized and pragmatic fashion. They do not just randomly pick a street or neighborhood to conduct their preaching work in. Instead, every section of the globe is divided up into territory regions. The more densely populated the area a further dividing of the territory is done: By continent, then country, then state or province, then city, and finally by neighborhood.

Each congregation is assigned a specific number of neighborhood territories to perform the preaching work in. The congregation meets together as one large group for all meetings held at the local meeting place called a Kingdom Hall [A hall or building where God's Kingdom with Christ Jesus as ruler is discussed].

 

However, for preaching purposes each individual congregation is organized into smaller preaching work groups called field service groups. Records are kept and audited to ensure that each neighborhood in the congregation's assigned territory is worked at a minimum goal of at least once a year, and also to prevent field service groups from duplicating their efforts by preaching in the same territory at the same time. 

Even with this organized preaching work structure, there are territories in remote areas of each territory region that due to climate, lack of road infrastructure, and not being a densely populated area requires volunteers from one congregation to be selected and approved to go and assist other congregations in need of help in covering their territory assignment. Some of these territories are not assigned to a specific congregation. They are called "Unassigned Territories". Note an example of this as described below: