Networks and The Internet

The OSI Model is a conceptual, implementation-neutral model that describes networking in seven separate layers, where each layer covers a set of functions and tasks.

This model helps us communicate while we do network troubleshooting and architecture.

The TCP/IP Model is an implementation-specific networking model that revolves around the TCP protocol and IP addressing which anchor the Internet as we know it.

Its layers include:

• The Network Layer
• The Internet Layer
• The Transport Layer
• The Application Layer

The OSI layers include: Physical, Data Link, Network, Transport, Session, Presentation, and Application.

• The Physical layer includes physical technologies
• The Data Link layer includes data framing and local MAC addressing
• The Network layer includes connecting to the larger web and IP addressing
• The Transport layer includes protocols that make sure reliable delivery happens
• The Session layer authenticates and maintains communication over a period of time
• The Presentation layer en/decrypts and translates data into presentable form
• The Application layer includes all the applications we interact with that render data

Three broad categories of networks include:

• Local Area Network (LAN), a smaller-sized network that connects multiple devices in a small area
• Campus Area Network (CAN), a larger network that connects multiple computers and devices over a slightly larger area
• Wide Area Network (WAN), the largest-sized network that connects multiple computers, over a geographically large area

The Internet is technically a WAN.

A network is two or more computers or devices that are linked in order to share information.

Networking refers to a large set of standards and protocols that organize and regulate the sharing of information.

A network protocol is a set of standards for Internet traffic.

Among them are the big transport protocols:

• TCP and UDP
• HTTP for web requests
• DNS to convert domain names to IP addresses
• IMAP/POP3 for email
• SSH
• FTP
• SMB for access to specific resources

The internet refers to the actual network of connected computing devices.

The world wide web is a collection of interlinked websites and other web resources that use the internet to share data.

The client-server model describes how the flow of data is transferred on the internet.

Web 2.0 applications provide a dynamic user experience by:

• Responding to user input without having to reload the page
• Emphasizing user-generated content and social sharing.

This was made possible through technical advances such as JQuery and web frameworks.

Mobile internet traffic accounts for more than half of all internet traffic and has caused web development practices to provide a good user experience regardless of device type.

Responsive web design allows the presentation of websites to adjust based on the size of the window in which they are displayed.

Mobile applications are not a part of the world wide web although most of them are connected to the internet.

Transmission Control Protocol and Internet Protocol (TCP/IP) are standards for data transfer which allow networks all over the globe to communicate with each other.