Let me describe for you an entire web design process with several sentences below. Generally it works for both – web sites and web applications.
- Drawing a sketch or concept (paper, whiteboard or any other surface)
- Creating a basic black and white wireframe (Visio or any wireframing tool)
- Designing a colorful high fidelity mock up (Photoshop, Illustrator, Axure, HTML)
- Developing a prototype (CSS, HTML)
- Responding to users feedback and updating design, delivering relevant screen designs to web developers