An encrypted web session is a browser connection protected by transport encryption, usually HTTPS/TLS, so intermediaries on the network cannot read the page content in transit. This protects logins, forms, messages, and other sensitive data from passive sniffing and many simple man-in-the-middle attacks.
It matters because encryption does not hide everything. Even when content is unreadable, observers may still learn metadata such as when a connection starts, how long it lasts, and which server is contacted. Attackers and censors can use that information for profiling, traffic analysis, or blocking. Defenders strengthen encrypted sessions with certificate validation, secure protocol settings, and privacy controls that reduce metadata leakage.