There are many tools available to create wireframes and prototypes, from lightweight and easy to use but with less functionality, to fully featured but with a high learning curve. It can be difficult to know which to choose. The trick is to choose those that work for you and your team, and stick with them until they don't. Some teams seem to change tools with every project. However, even the simplest tools take time to master; and even if the underlying task and workflow are similar there is always some cost to learning a new interface.
The following diagram shows some of the more common prototyping methods or tools, along the axes of purpose and learnability. Typically, tools that are what you see is what you get (WYSIWYG ...
