If you are a self employed web developer or if you are in charge of a website project for a client then it is important that everybody knows what is included in the build from the start, costs and also timescales. Every project should have a specification, an estimate or quote and also a timeline to show the dates that certain elements should be completed by. This is a way to ensure that everyone understands the timings and can be used for the programmer to also ensure that the information he / she requires to complete the job is received on time.
When deciding what is included on a website, it is sometimes worth creating a flow chart which details the pages / functions within the site. You may also want to create a wire frame that shows the layout of the website and possibly a visual of the home page or a product page for example. Doing this upfront can often allow both parties to pick up on additional things they wish to include or elements they want to remove or change prior to it going in to programming. Changes made after programming has commenced often will be charged for.