A wireframe is simply a diagram of your app. It doesn’t have to be beautiful. It does have to be comprehensive.
It is the link between what’s in your head, and what will eventually appear in physical form on the App Store or Google Play.
It needs to show everything that happens in the app, from splash screen to closing. How does one screen lead into the next? What content, information and navigational elements are included on each screen? Which elements have priority? What are the user’s escape routes out of each function or back to the home page?
What is a wireframe for?
It can help to refine and even enhance the original idea. It may uncover kinks/problems/omissions in the idea or its structure. It is invaluable in helping your developer to understand the scope of the app you are proposing. It defines the scope and objectives of the project, keeping all parties on track during development.
Wireframes may go through several revisions. At first they should be basic, not concerned with aesthetics or detail. The underlying structure needs to be right first, as all subsequent details will depend upon it.
Later levels of wireframing should involve your designer, and address the user interface and the look/feel of the app, artwork, colours, typography etc.
A good wireframe can save you much blood, sweat and tears during the development process. It can address pitfalls before you even start. It can be a map to guide you and your contractors through the process. It provides a common language and helps to avoid ambiguities, misunderstandings and scope creep.