User testing means watching real people use your product or prototype. It is the most reliable way to find out whether a design works.

How to run a session

• Give a concrete task (e.g. “find and buy a product”).
• Observe in silence without guiding the user.
• Note hesitations, errors and comments.
• Listen to what the person thinks out loud.

Good news: you do not need crowds. Testing with five people already uncovers the vast majority of major problems. The key is to stay neutral: if you have to explain how to do something, the interface is not clear enough. Every blocker you observe is a valuable chance to improve the product before it goes live.

Key takeaway: you are not your user. Observing beats assuming.