Theory [ARCHIVED]

• Most images are bitmaps which are made up of pixels
• The colour of each pixel is represented as a binary code
• The numbers of colours available relates to the number of bits the code has
• 1-bit images only use 2 colours, black(1) and white (0)
• 2-bit images use 4 colours so use a combination of binary codes to represent the colours
• To increase the range of colours, the colour depth (number of bits) needs to be increased
• To work out the total number of colours in an image

  -> Total Number of colours = 2^n (where n is bits per pixel)
• Most devices use 24-bit colour depth with 8 bits for the levels of red, green and blue
• The image resolution is the number of pixels in the image or width x height
• The higher the resolution, the more pixels the image is made of so the better quality of the image
• To work out the file size of the image -

  -> File size = image resolution X colour depth = width x height x colour depth
• A LAN is a local area network
• A LAN covers a small geographical area located on a single site
• All the hardware for a LAN is owned by the organisation that uses it
• With a LAN:

  • File sharing is easier
  • You can share the same hardware
  • The internet connection can be shared between every device
  • You can communicate cheaply and easily
  • You can install and update software on all computers at once
• A LAN can either be wired (Ethernet cables) or wireless (Wi-Fi)
• A WAN stands for a Wide Area Network
• A WAN connects LANs that are in different locations
• WANs are managed and owned by telecommunicatio companies as WANs are more expensive than LANs
• WANs can be connected using fibre optic cables or copper cables (as telephone lines, sattelite links or radio links)
• Fibre optic cables transmit data faster but they are more expensive to lay down
• The internet is one big WAN
• LANs have a high bandwidth which means it has the ability to transfer large amounts of data quickly
• WANs have a low bandwidth compared to LANs because there are many users sharing the same connection
• Bus Topology - all computers connect to a single cable called a backbone
• Star Topology - every device connects directly to a central hub/switch
• A network topology describes how devices on a computer network are arranged
• A client-server network is managaed by a server. The devices that are connected are the clients and files and software are stored centrally. The client sends requests to the server and the server processes the request and responds. The server stores user profiles, passwords and access information.
• In a Peer-to-Peer (P2P) network, all devices are equal, connecting directly to each other without a server. You can store files on individua; devices and share them with others.
• The advantages of P2P networks include no need for a dedicated server, easy setup and maintenance, and fast file transfer speeds.
• The disadvantages of P2P networks include security risks as data isn't encrypted when transferred between peers, potential loss of privacy due to shared resources, and slower performance if too many people are using it at once.
• Network protocols define rules for communication between devices on a network.
• Firewall: A firewall blocks unauthorised access to your system by monitoring incoming traffic and only permitting authorised connections.
• TCP/IP stands for Transmission Control Protocol / Internet Protocol. It is used to transmit packets across the internet and allows different types of hardware to communicate with one another.
• Cloud computing allows users to access their applications and data from any location via an internet connection. It provides scalability, flexibility, cost savings, and improved collaboration.
• HTTPS uses SSL/TLS encryption to secure communications over HTTP. This prevents unauthorized users from intercepting sensitive data transmitted over the web.
• FTP is an application layer protocol used to transfer large amounts of data such as images, videos, and documents. FTP allows multiple connections simultaneously which makes it ideal for downloading updates or uploading backups.
• Antivirus Software: Antivirus software scans your computer for viruses and malware and removes any threats found.
• Encryption: Encrypting sensitive data makes it difficult for attackers to read or steal.
• An Ethernet cable connects two or more computers together via an Ethernet hub or router.