A wireframe is a structural illustration represented as a black-and-white visual layout of a project. It can provide a method for prototyping, and make amendments of key elements simplified within a project. It may also create a dialogue between your team and the users of your project for a better understanding of functionality, user journey, and other key user experience requirements. Ultimately, a wireframe can build confidence in an idea and provide a new level of understanding to validate an assumption.
A wireframe is typically a dynamic document, constantly being updated to fit new requirements and knowledge. They include greater details than a sketch, but don't offer the aesthetic representation of a comp. They are most commonly associated with a User Experience specialist and are a key instrument in visually representing their findings.