Intro to Computer Science / Unit 9: The Internet and Networks
9.4 Protocols: TCP/IP, HTTP and HTTPS
Notes
A protocol is a set of rules that devices follow to communicate.
- IP handles addressing and routing. TCP makes sure packets arrive, in order, resending lost ones. Together they are TCP/IP.
- HTTP is the protocol that web browsers and servers use to request and send web pages. HTTPS is HTTP with encryption, shown by a padlock.
- Other protocols: SMTP (sending email), FTP (file transfer), UDP (fast but without guaranteed delivery, used in video calls and games).
- A browser sends an HTTP request, and the server sends back a response with a status code:
200means OK,404means page not found.
Practice
Which protocol encrypts the communication between a browser and a website?
HTTPS adds encryption to HTTP.
A browser shows "404". What happened?
404 means not found.
Which job does TCP perform?
TCP provides reliable delivery by tracking and resending packets.
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