After understanding your target audience, it is time to create a wireframe answering their needs. This will help them achieve their goals by, for example, easily providing the information they were looking for or buying a product.
Why a mockup? Because creating a website is like building a house, you need to think ahead rather than making (big) changes afterwards which is neither cost-effective nor time-saving.
Wireframe: A wireframe is a quick and rough sketch of your website, it needs to be easy to make and update. As an explanation, you would not start building a house without previously planning it.
Cost-effective: It means good value for money paid.
Users: They are the people who are going to use your website, your visitors, they can be your clients, patients, customers…
For complete website:
Projects start from £500.
E-commerce developement start from £2500.