[CrashCourse CS] #30 The World Wide Web

The World Wide Web runs on top of the Internet.
They not the same thing, although people often use the two terms interchangeably.

• Before hyperlinks were implemented, every time you wanted to switch to another piece of information on a computer, you had to rummage through the file system to find it, or type it into a search box.
• A unique address of each hypertext - URL, Uniform Resource Locator.

When a website is entered onto a browser...

ex) thecrashcourse.com/courses

1. DNS lookup - Takes domain name as input, and replies back with corresponding computer's IP address.
2. Web browser opens a TCP connection to a computer that's running a special piece of software called a web server.
   • The standard port number for web server is port 80.
3. Ask that web server for the hypertext page, using HTTP, Hypertext Transfer Protocol - send server GET /courses.
   • This command is sent as raw ASCII text to the web server, which then replies back with the web page hypertext requested.
4. This is interpreted by the computer's web browser and rendered to the screen.

• Web page hypertext is stored and sent as plain old text, for example encoded in ASCII or UTF-16.
• Because plain text files don't have a way to specify what's a link and what's not, it was necessary to develop a way to "mark up" a text file with hypertext elements - HTML, Hypertext Markup Language was developed.

Web Browsers

• Application that lets you talk with all the web servers.
• Broswers request pages and media, and also render the content that's being returned.
• The first web browser and web server was written by Tim Berners-Lee in 1990, released to the public in 1991.
• The web was an open standard, making it possible for anyone to develop new web servers and browsers.
• The Mosaic web browser(1993) - first browser to allow graphics to be embedded along side text, bookmarks, GUI.

Search Engine

• At first, people maintained web pages which served as directories hyperlinking to other websites.
• As the web grew, human-edited directories started to get unwieldy, and so search engines were developed.
• Early search engine - rank results by number of times a search term appeared on a page; problem was that people started gaming the system, like by writing "cat" hundereds of times web pages just to steer traffic their way.
• Google sidestepped this issue by looking at how other websites linked to a page; no site would link to a spam page, but if the webpage was an authority on cats, then other sites would likely link to it.

Net neutrality

Network neutrality is the principle that all packets on the internet should be treated equally.

• Net neutrality advocates argue that giving internet privders the ability to set up tolls on the internet to provide premium packet delivery plants the seeds for an exploitative business model.
• Net neutrality opponents argue that market forces and competition would discourage bad behavior, because customers would leave ISPs that are throttling sites they like.

Vocabulary

• delve into - 철저하게 조사하다
• rummage through - 뒤지다
• aptly - 적절히
• dreaded - 두려운
• unwieldy - 다루기 불편한
• game(v) - 게임을 하다
• reiterate - 반복하다
• conjecture - 추측

Thougts

이제 30강을 들었다. pbs cs 는 총 40강이며 이제 총 10강이 남았다. 강의를 다 들으면 정리한걸 다시한번 쭉 훓어보면서 cs 의 기초를 다질 생각이다.