A user agent is a software component that helps facilitate interactions between end-users and web content by sending a user agent string to servers, which identifies the browser, device, and operating system in use, allowing the server to tailor responses accordingly. In web scraping, using a recognizable user agent is crucial as servers often block requests from unrecognized or default user agents to prevent bot activity. To avoid being blocked, it's recommended to use real and popular user agents, rotate them, and ensure the headers match the user agent's expected behavior. Techniques such as using rotating proxies and setting up lists of user agent strings can help in randomizing requests, reducing the chances of being detected as a bot. For efficient data collection, automated solutions like Bright Data's Data Unlocking technology offer advanced features to generate site-specific user agents and bypass detection systems, enhancing the success of web scraping activities.