Non-linear access means you can look at the content in any order you choose, compared to a book where content is delivered in a specific order Page 1,2,3...
When you are designing a Navigation System decide on how to distribute the flow of information, then map it out using a series of flow charts or diagrams to represent this.
An interface design is result of design, planning and development based on the specifications outlined in a brief and the project is dealt with using a methodical approach to problem solving.
