# Networking 101: the basics of computer networks and the internet ## What is a computer network? A computer network is multiple computers that are connected so that they can communicate data electronically. They are built from hardware (e.g., routers, switches, hubs) and software. Connections are made using cables, fibre optics, or WiFi. Networks follow protocols which define how data packets are communicated between devices. Routers allow data to be communicated across different networks, while switches manage communication within a network. Devices each have a unique address which ensures data reaches the correct recipient. The internet is a network of networks that connects devices worldwide. Communication is achieved using standard protocols. ## Types of computer networks ![](https://i.imgur.com/F9GT5kf.jpg) There are different types of networks, some of which are defined by their geography. Some of the most common are: * **LAN (local area network)**: Connects computers across a single location (e.g., an office). They are usually privately owned. * **WAN (wide area network)**: Connects computers across different locations or worldwide (e.g., the internet). * **VPN (virtual provide network)**: A secure, encrypted channel which connects two endpoints. ## Network protocols A network protocol is a set of rules for how data is communicated between devices on a network. Data is sent between devices in data packets (also known as **datagrams**). These consist of raw data and a header; the header includes addresses of the sender and recipient. The arrival, content, and order of a data packet is not ensured. Each network device (or host) has a unique identifier (or address). These are used to ensure data is sent to the correct destination. Examples are: * **MAC (Media Access Control) addresses**: Unique identifiers assigned to every device during manufacturing. * **IP (Internet Protocol) addresses**: Unique identifiers which define a device’s host network and location. They are assigned to every device using the Internet Protocol to communicate. Ports are logical channels which allow data to be routed to a specific application or service within a host. They are identified by unique numbers. A combination of an IP address and port number specifies a particular service on a particular host. ## Network communication protocols Network communication protocols provide standards for creating and keeping connections between network devices. The following protocols are key to the functioning of the internet: * **TCP (transmission control protocol)**: Chunks data into packets which can be sent across an IP-based network. * **IP (internet protocol)**: Responsible for assigning sender and destination addresses to the header of a data packet. * **UDP (user data protocol)**: Used for establishing low-latency and loss-toleration in communications between applications. * **HTTP (hypertext transfer protocol**): Uses TCP/IP to deliver webpage content from a server to a browser. * **FTP (file transfer protocol)**: Used to deliver files between computers on a network. ## Network security protocols There are also various protocols which increase network security and prevent cyberattacks like eavesdropping. Common examples include: * **SSL (secure socket layer)**: Creates an encrypted connection between a computer and the server over the internet. * **TLS (transfer layer security)**: The more robust successor to SSL. * **HTTPS (hypertext transfer protocol secure)**: Modifies HTTP to use TSL and encrypt the connection between the web browser and a server. * **SSH (secure shell)**: Provides an encrypted connection between computer and a server. It supports a variety of authentication methods. ## Internet Protocol suite The Internet Protocol suite (also known as **TCP/IP**) outlines how protocols can be combined to enable end-to-end communication between devices over an IP network. It has **4 layers**: ![](https://i.imgur.com/DBugNJp.jpg) * **Application layer**: Defines how network devices create and share data with other applications. It is concerned with using the appropriate protocol for the type of data being sent. * **Transport layer**: Performs host to host communication. * **Network layer** (or **Internet layer**): Responsible for exchanging datagrams across networks. * **Link layer**: The networking methods which hosts use to communicate. It is the physical mechanism for sending digital data. The internet protocol suite is the ‘Network Layer’ of the comprehensive OSI (open systems interconnection) model. This has 7 abstract layers which provide a standard for devices and systems to communicate with each other. In comparison to the Internet Protocol suite, it is more general; the modern internet more closely follows the Internet Protocol suite.
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Muhammad Abdulhadi
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Team 2

The Problem :no_entry_sign: :- Patients find it hard to book an appointment in a dental clinic, they would make a call, or they would come to the clinic to book an appointment, and sometimes they would come to it and wait in a queue to meet the doctor without any previous booking. The Dentist faces hardships to manage patients' appointments, their payment schedules, and their history manually.That would cause huge problems like wasting some time and effort and tripling some customers with the repeated data requests. Doctors encounter these problems to track the patients' histories, and all of these operations are done with paperwork that is not durable. The solution :bulb: :- Use the technology to create a smooth and tidy system, also employment its advantages in durability by creating a web application to provide the specific requirements include a booking form and database history for every patient. So that saves time and effort for the dentist and helps the patients with their reservation for an appointment. User Stories :books: User who want to register an appointment :pill: As a patient, I want to book an appointment at a specific time and date and personal details like a name and birthday. So I can save my time and effort.

6/4/2023
Node.js

Introduction to Node.js What is Node.js ? Node.js is an open-source and cross-platform JavaScript runtime environment. It is a popular tool for almost any kind of project! Node.js runs the V8 JavaScript engine, Google Chrome's core, outside the browser. This allows Node.js to be very performant. A Node.js app runs in a single process, without creating a new thread for every request. Node.js provides a set of asynchronous I/O primitives in its standard library that prevent JavaScript code from blocking and generally, libraries in Node.js are written using non-blocking paradigms, making blocking behavior the exception rather than the norm. Why use Node.js ? Node.js is a cross-platform runtime, perfect for a wide range of use cases. Its huge community makes it easy to get started. It uses the V8 engine to compile JavaScript and runs at lightning-fast speeds. Node.js applications are very scalable and maintainable. Cross-platform support allows the creation of all kinds of applications - desktop apps, software as a service, and even mobile applications. Node.js is perfect for data-intensive and real-time applications since it uses an event-driven, non-blocking I/O model, making it lightweight and efficient. With such a huge community, a vast collection of Node.js packages is available to simplify and boost development. I/O Examples The diagram shows that a single node process (the hexagon in the middle) can act as the broker between all of the different I/O endpoints (orange and purple represent I/O).

3/17/2023
Week 2 Projects Review

README !! File Structure could be enhanced instead of putting everything in the root, or all the CSS code in one file and remove unused files or folders. Git & GitHub Don't push to main or update directly from GitHub even if it was just a README PR requires all the team members to approve it after they review it since they will become responsible once it is merged. Write a good descriptive name for the PR and write a good commit message, use labels correctly, and make your commits small. You should distribute tasks fairly so if you ever felt left behind speak to us privately and we will take action immediately without anyone knowing. Consistency: let/const and es6/es5. Remove any console.log and you should always check the console log if there are any errors and solve them. Remove and unused commented lines of code and don't merge them with main.

3/10/2023
Team 5

The Problem :no_entry_sign: :- Patients find it hard to book an appointment in a dental clinic, they would make a call, or they would come to the clinic to book an appointment, and sometimes they would come to it and wait in a queue to meet the doctor without any previous booking. The Dentist faces hardships to manage patients' appointments, their payment schedules, and their history manually.That would cause huge problems like wasting some time and effort and tripling some customers with the repeated data requests. Doctors encounter these problems to track the patients' histories, and all of these operations are done with paperwork that is not durable. The solution :bulb: :- Use the technology to create a smooth and tidy system, also employment its advantages in durability by creating a web application to provide the specific requirements include a booking form and database history for every patient. So that saves time and effort for the dentist and helps the patients with their reservation for an appointment.

10/5/2022
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