Networks
- A network is two or more computers connected to share data and resources.
- A LAN (local area network) covers a small area, such as a home or school. A WAN (wide area network) covers a large area; the internet is the biggest WAN.
- Networks let people share files, printers and internet connections, but viruses can spread and they need to be kept secure.
- Hardware: routers direct data between networks, switches connect devices in a LAN, and wireless access points provide Wi-Fi. Data travels through copper cables, fibre-optic cables (pulses of light) and radio waves.
The internet and the Web
- The internet is the worldwide network of networks: the cables, routers and connections.
- The World Wide Web is a service that runs on the internet: web pages linked by hyperlinks and viewed in a browser.
- Every device on a network has an IP address. The domain name system (DNS) turns web addresses such as www.example.com into IP addresses.
Sending data
- Data is split into packets. Each packet carries the destination address and a number, so the packets can take different routes and be put back in order.
- A protocol is a set of rules for communicating: HTTP and HTTPS for web pages (the S means secure, because data is encrypted), and SMTP for sending email.
- Bandwidth is the amount of data that can be sent each second, measured in megabits per second (Mbps).
- Search engines use web crawlers to visit pages and build an index, then rank the results.
Key terms
- Network
- Two or more computers connected to share data and resources.
- LAN
- A local area network, covering a small area.
- WAN
- A wide area network, covering a large area.
- Internet
- The worldwide network of networks.
- World Wide Web
- Web pages linked by hyperlinks, viewed over the internet.
- Router
- A device that directs data between networks.
- IP address
- A unique number that identifies a device on a network.
- DNS
- The system that turns web addresses into IP addresses.
- Packet
- A small chunk of data sent across a network.
- Protocol
- A set of rules for how devices communicate.
- Bandwidth
- The amount of data that can be sent each second.
- Browser
- Software used to view web pages.