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tags: mstu5013
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# What's internet?

Internet is a network of computer devices connected together through underground and undersea cables, and wireless routers.
https://www.youtube.com/watch?v=7_LPdttKXPc

## Internet Servers and Clients
Internet servers make the Internet possible. All of the machines on the Internet are either servers or clients. The machines that provide services to other machines are servers. And the machines that are used to connect to those services are clients. There are Web servers, e-mail servers, FTP servers and so on serving the needs of Internet users all over the world.

## IP address
A server has a static IP address that does not change very often. A home machine that is dialing up through a modem, on the other hand, typically has an IP address assigned by the ISP every time you dial in. That IP address is unique for your session -- it may be different the next time you dial in. This way, an ISP only needs one IP address for each modem it supports, rather than one for each customer.

## Website hosting


Web hosts are companies that rent out their services and technologies to host websites on the internet. Once the hosting company hosts your website, users can access it by typing in your web address (domain name) in their web browser. When they do this, their computer connects to the server your website is hosted on. The server in turn serves (sends the files you have stored on the storage to display) the website to your web visitor in their web browser.

## Database

A database is a collection of information organized in such a way that a computer program can quickly select desired pieces of data.

You can think of a traditional database as an electronic filing system, organized by fields, records, and files. **A field** is a single piece of information; **a record** is one complete set of fields; and **a file** is a collection of records. For example, a telephone book is analogous to a file. It contains a list of records, each of which consists of three fields: name, address, and telephone number.

### relation vs. nonrelational DB

##### mySQL, a popular enterprise level relational database 

##### mongoDB, a popular non-relational database

Relational: Better when data structure fits nicely into table and rows. Or Require SQL or transactions

Non-relationnal: Better when data seems complex in relational database system. Or De-normalizing database schema or coding around performance. Or Can not pre-define schema or want to store records in same collection that have different fields.

## Firebase, a non-relational, cloud based database service

https://www.youtube.com/watch?v=JrHT1iqSrAQ