Unit 5.1 - the Internet and the WWW Flashcards
(17 cards)
What is the Internet + physical attributes?
A global, public, interconnected network made out of series of computers and networks. It is the physical infrastructure that allows data to be transmitted across the globe.
Physical attributes: computers, servers, switches, routers, cables, etc.
What is the backbone of the Internet?
The cables that run underneath the ocean, connecting the world via the Internet.
What is the WWW + resources?
The world wide web is the collection of resources on/accessed via the Internet. Such resources include web pages, websites, documents, images, videos, music, emails, etc. You need to have an Internet connection to access the WWW.
What is a URL + 3 parts?
A uniform resource locator is a unique, text-based address of a web page/other resource. It is memorable and user-friendly to find the web pages easily. The URL is used by humans but computers on the Internet only use the numerical IP addresses of the server which holds the web page/
Made of 3 parts: the protocol used (http or https); the domain name (e.g. brainscape.com); and the file name. Some URLs will have the file path, which shows the directories or folders that lead to the location of a specific file on the server.
What is assigned to each device on a network?
An IP address
What is HTTP and HTTPS?
HTTP - the hypertext transfer protocol; set or rules about how information is requested/transferred between the client and the server. Transmits data in plaintext.
HTTPS - hypertext transfer protocol secure; same as HTTP but information is encrypted.
What are the 4 request codes HTTP uses to send and receive data & perform other tasks?
- GET - request asks web server to transmit specific resource like web page, to the user’s web browser
- POST - request adds content, messages or data to a new page under an existing web resource
- DELETE - request removes specified resource from web server
- PUT - request modifies an existing resource
How does HTTPS work?
It obfuscates (turns human-readable data into a format which doesn’t make sense) data using a method called Transport Layer Security. This uses 2 different keys to encrypt data - private key (controlled by owner of website) and public key (available to anyone who interacts with server in a secure way).
What is a web browser + examples + functions?
A special type of software that allows us to view & access resources on the WWW. It has many functions such as:
1. Translating HTML and displaying the visual representation which allows us to view web pages
2. Store history, bookmarks and favorites
3. Allow use of multiple tabs simultaneously
4. Store cookies
5. Provides navigation tools like back, reload, home, add tab, etc.
6. Provide address bar to browse web pages of your choice
Examples: Chrome, FireFox, Opera, Microsoft Edge
What is HTML?
Hypertext mark-up language (not programming language). It defines and structures the content of most web-pages.
What is DNS?
Domain name system. A DNS server is an address book which keeps a record of all domains in existence, which matches URL to IP address. If one DNS server cannot find the record of the domain and IP address, it will request this information from another DNS server.
How do we access web pages on the Internet in 5 steps?
- The client requests web page by entering URL into an address bar in a web browser
- This request goes to the DNS server, which matches the URL with the IP address
- Then, the web server receives this IP address and visits the web server at the address in question
- The web server grants access to the resource, returning it to the requesting web browser
- Finally, the web browser translates the raw HTML into a readable format for users
Flow: web browser - DNS server - web browser - web server - web browser
What is a web server?
A computer system connected to the Internet that stores and hosts web resources (such as web pages and images) and delivers them to users/other computer systems over the web when requested
What is CSS?
Cascading style sheets are used to add formation and styles to HTML.
What are cookies?
Small piece of data in the form of text files stored by the web browser (locally). They are created when you visit certain websites, and allow them to remember your activity, preferences, login details, credit card info, holding items in shopping cart, etc. They are not harmful.
Persistent vs session cookies
Persistent cookies - stored long-term on the computer system in a hard disk drive. Data stored on these cookies will be used whenever that user browses the website until their expiration date. Stored on hard disk drive. E.g. storing login details
Session cookies - deleted after closing the browser/logging out of website (end of session), exists in memory (RAM) temporarily. No expiration date. Typically used when browsing sensitive information like online banking or shopping cart items.
What are examples of 3 attributes a persistent cookie may store?
- Theme - website theme (light or dark)
- Customer ID
- Expiration date - when it stops being stored
