One or more high-fidelity mockups delivered in the early phases of product ideation. It depicts what problems the product will solve, how it might solve them today and in the future, and what the product will feel like to the end user. Concept designs are deeply impacted by user research and kick off the entire product design phase.
Here's an analogy.
Just like an architectural drawing gives homeowners an idea of what their new home might look like and what materials will bring it to life, a concept design shows how a digital product might look and the important pieces going into its construction.
Why does it matter?
Concept designs are ideal for honing a product vision, getting a glimpse into future functionality, and generating excitement & buy-in among key stakeholders.
How does it apply?
A concept design is the first stage of bringing a digital product to life through compelling visuals.