Internet, Browsing and Email
What to know
The internet is a network of networks; the web is one service running on it. A URL names a protocol (http or https), a domain (example.org) and often a path. HTTPS encrypts traffic between browser and server, and the padlock means the connection is secure, not that the site is trustworthy. DNS translates domain names into IP addresses. Browsers store bookmarks (saved addresses), history, cache (copies of page files that speed reloading and can serve stale content) and cookies (small site-specific data files, often keeping you logged in). Private or incognito mode limits local history and cookies but does not hide activity from a network or ISP.
For email, SMTP sends mail while IMAP and POP3 retrieve it. IMAP keeps messages on the server and syncs across devices; POP3 typically downloads them to one device. To hides recipients, CC is visible to everyone, Reply answers the sender, Reply All answers the sender plus everyone copied, and Forward passes the message on. Attachments travel with the message and are subject to size limits.
Traps
The padlock does not certify honesty. Deleting browser history does not delete cookies or the server's records. BCC recipients cannot see one another. A misspelled domain in a link is a classic phishing sign.
Worked example
Sending a newsletter to 50 parents: place all addresses in BCC so no recipient's address is exposed to the others.