3G communication
1. It stands for 3^rd generation technology.
2. Maximum upload rate of 3 G technology is 5 Mbps.
3. Maximum download rate of 3 G technology is 21 Mbps.
4. It uses packet switching technique.
5. The frequency range of 3 G technology is from 1.8 GHz to 2.5 GHz
4G communication
1. It stands for 4^rd generation technology.
2. Maximum upload rate of 4 G technology is 500 Mbps.
3. Maximum download rate of 4 G technology is 1 Gbps.
4. It uses packet switching technique as well as message switching technique.
5. Its frequency range is from 4 G technology is from 2 GHz to 8 GHz.

(i) Network is a broad term similar to system. Network is a communication system which supports many users. In relation with the computers, we can say that a "computer network" is a system which allows communication among computers connected in the network.
(ii) A computer network is the interconnection of two or more computers. It is done to enable the computers to communicate and share the available resources.

(i) Spam can be defined as irrelevant or unsolicited messages sent over the internet. These are usually sent to a large number of users for advertising, phishing, spreading malware, etc.
(ii) Spamming is the process of sending digital junk mail: unsolicited communication sent in bulk over the internet or through any electronic messaging system.

(i) Ecommerce or electronic commerce refers to transactions conducted via the internet. Ever time individual and companies are buying or selling products and services online they are engaging in ecommerce.
(ii) Ecommerce is a popular term for electronic commerce or even internet commerce.
(iii) Examples of ecommerce: Amazon, flipkart, eBay, Olx, Quikr,

(i) Network is a broad term similar to "system". Network is a communication system which supports many users. In relation with the computer, we can say that a "computer network" is a system which allows communication among the computers connected in the network.
(ii) In a computer network, we need to make use of hardware and software. The hardware consists of connecting cables, connectors, network connecting devices and the software consists of protocols, programs, etc. This enables the systematic exchange of information between the computers connected in the network.