What is usability testing and what do moderated sessions and tasks measure?

Usability testing is observing (often 5–8 participants per round is a common small sample) as they try to complete realistic tasks. You measure things like: did they complete the task, how long, where they hesitated, and what they misunderstood. A moderator asks them to think aloud, avoids leading questions, and does not 'help' too early. Unmoderated remote tests and screen recordings scale patterns but lose some context. A/B tests measure conversion in production; usability tests explain why. You write a test plan, recruit people who match target users, and iterate designs between rounds. 'Everyone in the office clicked through' is not a replacement for a structured protocol.

Task: 'You need to add a new payment method to your account.'
# Observe: path, errors, and quotes. Do not 'just fix the button' from one person only.

Start simple: try this concept in a tiny project before moving to advanced tools.