Computer Fundamentals 简明教程

End Devices − End devices include PCs, cellphones, tablets, servers, IoT devices, etc. at the network edge. These devices produce and use data.

Network Infrastructure − Routers, switches, cables, fibre-optic lines, satellites, and wireless access points are all part of the network. Data travels between end devices via network infrastructure.

Protocols − Protocols regulate network data and how it is received. The modern Internet is based on the Internet Protocol Suite (TCP/IP), which includes − Internet Protocol (IP) − This protocol is responsible for addressing and routing packets of data so they can travel across the network. Transmission Control Protocol (TCP) − TCP establishes connections, acknowledges data, and retransmits missing packets to make sure that data packets are transferred securely and in sequence. User Datagram Protocol (UDP) − UDP, unlike TCP, is a connectionless protocol that does not ensure reliable delivery. It is frequently employed in real-time applications where a tiny delay is preferable to data loss.

Internet Service Providers (ISPs) − ISPs are firms that provide internet connection to customers, companies, and other organisations. They maintain the physical infrastructure and connections that allow people to access the internet.

Interconnectedness − The internet is made up of many networks. Small local area networks (LANs) in homes and businesses to worldwide networks controlled by ISPs, corporations, and governments are examples of these networks. These networks are linked by routers, switches, and other networking devices.

Communication Infrastructure − The basic objective of a network is to make it easier for devices to communicate with one another and share information.

Hierarchical Structure − Many networks, including the Internet, are hierarchical. At the lowest level, devices are connected locally. The global internet is formed by connecting small networks to larger networks in a hierarchical framework. Hierarchical organisation streamlines data routing and management.

Distributed Control − Distributed control models are used on networks like the Internet. Instead, ISPs, network managers, and users share control. This distributed control keeps the internet stable, resilient, and secure.

Packets When data is transmitted over the Internet, it is first divided into smaller packets, which are then converted into bits. Different networking equipment, such as routers and switches, route packets to their intended destinations; when the packets arrive at their destination, the receiving device reassembles them in the proper order before using or displaying the data. Packet switching is the transfer of small pieces of data across networks. Packets of data allow faster, more efficient data transfer. User-sent files are often sent in smaller data packets over networks. A 3MB file will be broken into packets with packet headers that specify the origin IP address, destination IP address, number of packets, and sequence number.

Protocols The Internet is based on a collection of standardised communication protocols known as the Internet Protocol Suite, or TCP/IP (Transmission Control Protocol/Internet Protocol). This protocol stack ensures that data packets are consistently and efficiently sent over the network. In addition to the basic protocol, there are some other protocols for routing, testing, and encryption.

Routers A router is a device that sends data packets across different computer networks based on the destination of the packets. Routers are like traffic cops of the Internet; they make sure that data goes to the right networks.

Switches Switches link networked devices. Packet switching routes packets to the right devices. These devices send outgoing packets to them, which they route.

DNS Web servers are specialised computers that are equipped with a high level of processing power. They are responsible for storing and delivering content (webpages, photos, and videos) to users. In addition, servers are responsible for responding to DNS inquiries and carrying out a variety of other essential activities to ensure that the Internet remains operational. The vast majority of servers are stored in massive data centres, which can be found in many parts of the world.

Early Concepts (1960s) − A decentralised network of computers was first envisioned in the early 1960s by scholars like J.C.R. Licklider and Leonard Kleinrock The Advanced Research Projects Agency Network (ARPANET), which was supported by the United States Department of Defence, became the first operational packet-switched network in 1969.

Development of Protocols (1970s) − The 1970s saw important networking protocol advancements. Vinton Cerf and Robert Kahn created TCP/IP to standardise network data transport. Ray Tomlinson’s design of the first email client and SMTP protocols enhanced network communication capabilities.

Expansion and Commercialization (1980s) − The 1980s saw the expansion of the internet. In 1986, the National Science Foundation Network (NSFNET) was founded to connect educational and scientific institutions and organisations located all over the United States. In 1989, Tim Berners-Lee introduced the World Wide Web (WWW), a system of hyperlinked documents accessible online, revolutionising the internet.

Growth (1990s) − The 1990s saw the internet commercialise and grow rapidly, driven by commercial ISPs and graphical browsers. The introduction of web browsers like Mosaic, Netscape Navigator, and Internet Explorer increased internet accessibility for the public. E-commerce, online banking, and social networking sites emerged, transforming the Internet for business and social interaction.

Mobile Internet and Social Media (2000s - 2010s) − Smartphones and wireless networks led to an increase in mobile internet access in the 2000s and 2010s. Facebook, Twitter, and YouTube became popular online platforms, enabling global communication and content sharing.

Internet of Things (IoT) and Future Trends (2010s - present) − The Internet of things (IoT) connects everyday objects and devices to the Internet, allowing new applications and services. Emerging technologies like AI, blockchain, and 5G networks are driving internet innovation and transformation.

Communication − The internet allows instant contact using email, messaging apps, social media, and voice/video calls. It keeps people in touch with friends, family, co-workers, and communities worldwide.

24/7 Information Access − The internet provides access to a vast repository of information on virtually any topic imaginable. Users can search for news, research papers, tutorials, and educational resources, which allows them to gain information and valuable insights.

Entertainment − The internet offers a plethora of entertainment options, including Movie, TV, music, and podcast streaming services available online. Social media, online gaming, and digital art platforms also enrich internet entertainment.

E-commerce − Online shopping has revolutionised retail, letting people shop from home. E-commerce platforms offer a vast selection, reasonable pricing, and easy payment and delivery.

Education − Online courses, virtual classrooms, and instructional materials have changed education. Students can learn new skills, get degrees, and participate in learning regardless of location.

Business and Entrepreneurship − The advent of the internet has provided businesses, effectively engage with customers, promote and sell their products or services, and facilitate online transactions. Furthermore, it has enabled entrepreneurs to initiate new businesses, market and sell products on online commerce platforms, and reach international markets.

Social Networking − Social media platforms such as Facebook, Twitter, Instagram, and LinkedIn enable users to interact with others, exchange material, and participate in debates. Social networking has become an essential part of Internet communication and community formation.

Healthcare − The internet allows for telemedicine, remote consultations, and access to health information and resources. Patients can make appointments, renew medicines, and seek medical advice online, making healthcare more accessible and convenient.

Government Services − Many government services are now available online, such as tax filing, permit applications, voter registration, and access to public data. E-government initiatives improve administrative operations and citizen engagement.