I use Axure RP at the start of a project during both the Research and Design phases of a project.
During the Research phase, here are some of the deliverables you can create in Axure RP.
Sitemaps — the overall architecture of a site
Personas — your target user needs and pain points
User Workflows — A specific set of steps a user goes through to complete a task
Customer journey maps — All the touch points, pain points and opportunities your customer go through when using your service.
During the Design phase, here are some of the deliverables you can create in Axure RP.
Wireframes — Structural layout of content and functionality of a website or mobile app
Prototypes — Interactive wireframes
Specification document — Handover document to developer detailing the scope of design work
Links to these downloadable free and premium Axure templates can be found at Humbleux.
As you can see you can achieve a very high level of detail/fidelity depending on what you are trying to convey and how much time you have on a project.
For me, it’s a great tool to tell and present the entire story of how you as a designer got to a solution for the client or to your team.
To learn more here is a video on what Axure RP is.
Axure vs Sketch