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Internet - Coggle Diagram

- - - - 8 bits = 1 Byte
        1024 Bytes = 1KB
        1024 KB = 1MB
        and so on...
  - - - Ethernet cables
      - Cheap
      - Signal loss
    - - Really fast
      - No signal loss
      - Fiber optic cables
      - Expensive
      - Hard to work with
    - - Wireless
      - Totally mobile
      - Short range
    - - Number of bits that can be sent over a period of time (usually seconds)
    - - Maximum transmission capacity of a device
- - - - Isn't enough
  - - - splitted up into zones (.org; .com; .net)
    - - Susceptible to cyberattacks
        
        DNS spoofing
        
        When a hacker enters into a domain and changes it so all the people that want to enter that website, will be visiting the fake website.
- - - - A Distributed Denial of Service attack is made with a bot net. Which are a lot of infected devices. Using this bot net, hackers can overwhelm server with too many requests
    - - To send a lot of spam e-mails to then try to trick people into sharing personal information
    - - A program that gets installed, oftenly unintentionally, that can spread easily just like a real life virus
        
        It can steal or delete files, control programs or allow someone else to control your computer
- - - - So, instead of moving up the same amount of times for each letter, you could change the number of moves up and down
        
        This is unsolvable for human beings, but computers could do it in seconds
        
        So, computers use a 256 bit long key to encrypt messages.
        
        When both computers share the same key to encrypt and decrypt a message, it is called symmetric encryption
        
        This is not safe at all because internet is open and public so anyone could see that key
        
        So, computers use asymetric encryption
        
        1 more item...
- - - - A program called spider is constanly travelling the web using hyperlinks and collect information about them and adding them to a database called search index
        
        When you search something, all of the words in the prompt are located in the search index and determines the best matches.
        
        Each web browser has its own searching algorithm based on what they think what you want
        
        A famous searching algorithm is page rank. It count how many web pages are linked to a certain page. The most links, the higher the rank
        
        Since a website makes money out of visits, spammers try to find new ways to get higher when you look up something, and therefore get more visits
        
        Searching algorithms get constantly updated to detect suspicious webpages and preventing them from reaching the top
        
        It is up to you to keep an eye on what pages to go on to and to make sure they're safe looking at the HTTPS and the lock to its left
- - - - Computers called routers will lead these packages to its final destination
        
        Router will see all of the available routes to send the information and will choose the route which is the most quick
        
        Sometimes, the most quick route isn't the most direct
        
        As routers have many routes available, even if something goes wrong, they could still send information
        
        The network is fault tolerant
        
        Reliability
        
        How can we make sure that the 100% of the information sent will arrive?
        
        TCP (Transmission control protocol)
        
        Once the packets have arrived, the TCP makes sure that no packages are missing. If there are packages missing, the missing packages will going to be sent again.
        
        Routers and TCPs are completely scalable. Which means that they could work with 8 packages or 8 billion packages without any problem.
- - - - HTTP stands for HyperText Transfer Protocol
      - When the computer talks to the server, mainly what the computer sends is Get requests
        
        It's just "get document-name"
        
        So, if you are requesting to log in into instagram, the computer will ask for the login page
        
        And the server will provide the HTML code for that login page
        
        HTML stands for HyperText Markup Language
        
        You don't only send get requests. Sometimes, you also send information
        
        You send information with a post request
        
        Websites remember who you are using cookie data
      - The internet is completely open, has all of its concetions shared and all of the information is sent in plain text
        
        This means that hackers can see all of your information over the internet
        
        Safe websites prevent this from happening by communicating on a secure channel
        
        Using Secure Sockets Layer (SSL) and Transport Layer Security (TLS)
        
        Always active
        
        When you see a lock next to the HTTPS (HyperText Transport Protocol Secure)
        
        When you try to connect on a secure webpage, it first provides a digital certificate that proves that the website you are visiting is really that website.
        
        Digital certificates are published by certificate authorities which are trusted entities that verify identities of websites and provides certificates for them
        
        If that website has not a digital certificate, it will warn you