A Network is a group of connected devices capable of communicating. The device can be a computer, printer, or scanner that either receives or transmits data. The devices connected in the Network are called "Nodes," and the means of connection can be wired or wireless.

This tutorial explains the criteria a computer network must attain to fulfill all the connected nodes' needs properly.

There are a lot of criteria that make a network better than others, but; there are three basic yet important criteria to be fulfilled for a network:

1. Performance
2. Reliability
3. Security

Performance

It measures how well a network can support communication between two nodes in the Network or with nodes of other networks in the global scope. The two major tasks in a network are the Transmission and reception of information. We need to focus on how fast a message is transmitted and how fast a node can receive a request and find the needed information. Hence, to measure the performance of a network, here are the major factors to be considered:

1. Transit time: The total time a node takes to transmit a message from the beginning until the last character of the message. Transit stands for Transmission.
2. Response time: The total time a node takes to process an inquiry or a request from another node/ device and respond. It is the time between the inquiry's end and the response's beginning.
3. Throughput: Throughput measures how much data is transferred successfully from the sender node to the receiver node in a particular time frame. It is measured in bits per second or data per second.
4. Bandwidth: The maximum possible throughput capacity of the Network. We can measure it in bits, megabits, or gigabits per second. It defines the highest limit.
5. Delay/ Latency: As we discussed, Throughput is the number of data packets successfully delivered in a given time. Delay is the measure of time taken to do the delivery.

Important points:

1. A network with high Throughput and less latency is ideal, but Throughput and latency always lie on two sides of the coin and are always proportional. If we try to automatically increase the data packet transfer, the time taken is also increased.
2. Throughput and bandwidth might seem similar, but they are different. Bandwidth is conceptual, while Throughput is practical. Bandwidth is like the vehicle limit of a highway. The number of vehicles/ data packets we are allowing is the Throughput.
3. Both Bandwidth and Throughput are important for the Network's speed. For fast data transfer, we can transfer more data packets, but too much data/ vehicles reduce the speed and might cause congestion; there is only one way than making the bandwidth wider. Hence, bandwidth is important though conceptual.
4. Several other factors influence a network's performance:
   1. Number of users
   2. Hardware capability
   3. Transmission media used.
   4. Software efficiency
   5. Jitter (disturbance)
5. Latency and Throughput are the two networking metrics that are periodically measured to keep up with the performance of the Network.

Reliability

It is the degree to which a network is trustworthy, consistent, and dependable. The Reliability of a network is measured by the frequency of failures it is undergoing and the time it takes to recover from the failures. Overall, the Robustness of the Network at times of catastrophic events is measured to check how reliable the Network is.

Security

It measures how the Network secures the data amid failures and attacks and the policies and procedures it implements to protect itself from damages and unauthorized access. In Reliability, the frequency of failures is checked. In Security, network attacks and data breaches are checked.

Overall goals of a typical network:

1. Scarce resources sharing
2. Feasibility
3. Better performance
4. High Reliability
5. High Security
6. Inter-process communications
7. Flexible access to authorized clients

Final Summary about the three major Network criteria:

1. Performance: The performance of a network is measured by measuring the Throughput and Delay of the Network. The ideal type of Network is supposed to have high Throughput and low delay, which are two proportional metrics. Other important factors determining a network's performance are Transit time and Response time.
2. Reliability: The Reliability of a network lies in how robust the Network is amid sudden major catastrophic events/ failures.
3. Security: It is how the Network protects all the important data and information at times of data breaches, unauthorized logins, damages, and viruses.