Wireframes are one of the early building blocks in creating the websites and applications we all use today. These quick, simple line drawings are the basic elements in the design process, created by the user interface (UI) designer after the initial meetings with the user experience (UX) team and the client to understand their needs. The results are refined by the UI designer until approved, then handed to the development team to create the final.
This is what I do for a living. I used Balsamiq to create these sample wireframes of my website. Most frequently I use Adobe Illustrator, but PowerPoint and plain old pencil and paper can be useful as well.