I think WiKi has quite comprehensive description:

https://en.wikipedia.org/wiki/Internet_of_things

To summarize, it's just a network of "intelligent" devices connected for exchange of data purposes - you can then control them easily, as well gather a lot of data for statistical purposes - that's why we also are saying about new concepts such as Big Data, Data Science, Machine Learning.

try this web site

https://www.tutorialspoint.com/internet_of_things/

Create your first  Internet of Things application in under 30 minutes with IBM Bluemix

https://yourstory.com/2015/03/internet-of-things-application/

Dear Syamsul,

The essay below has been written by "Abdul Subhani - President & CEO - Centex Technologies". A very interesting explanation about the implications of the Internet of Things:

It was only a decade ago that the Internet was primarily used and accessed by desktop and laptop computers. Today, mobile devices (phones, tablets, etc.) are quickly becoming the bulk of devices connected to Internet. Additionally, many types of sensors, instruments and devices are also seeking Internet connectivity.

However, some of the most significant Internet-related growth in the coming years will be from what is called the Internet of Things (IoT)—a number of objects hooking to Internet, some of which are hard to imagine even now: refrigerators, microwave ovens, bridges, traffic signals & lights, gates, etc. IoT allows users to sense and control objects through existing network infrastructure, such as Internet, with expected results including increased efficiency, better accuracy and added economic paybacks. 

What could be the ‘things’ in IoT?

A wide variety of objects are included in IoT. These objects are “things” such as sensors, automobiles, environment monitoring devices, household utility devices, or medical instruments like cardiac monitors, etc. These “things” can be a mix of hardware, software and services. Any object with a sensory component and some associated data can be part of IoT. For example, a refrigerator may need to sense conditions such as the change in temperature or the present position of food in the refrigerator, and it can have associated data about its internal temperature, the amount of food in it, and other relevant information. A refrigerator with those capabilities would be a viable candidate for IoT.

How does IoT work?

IoT is the connectivity of candidate objects over a common network, such as Internet. For those objects to be able to communicate on the network in easily understandable language, special, concise interfaces must be prepared. Currently, connectivity to IoT consists of hooking up a candidate to the network, wired or wirelessly, assigning an IP address to the candidate, and providing the candidate with the necessary bandwidth to communicate. But there must also be agreement between the candidate and the rest of IoT regarding what data is to be communicated and how it will be understood by others on the network. For this agreement to work, IoT candidates must be prepared with the necessary languages, protocols, or other skills needed to communicate over the IoT. With the huge number of objects predicted to be on IoT in near future, allowing so many objects to communicate with each other promises to be gigantic task.

A reliable IoT requires the following components:

Network infrastructure

Today’s Internet, with its typical expansion rate, is the best-suited network for hosting IoT objects. However, it still leaves room for improvement. As and when more objects form part of the network, the backbone bandwidth must also be enhanced. Fortunately, the Internet has proven that network expansion can such enhancements with little trouble. 

The ‘things’

Manufacturers who want their products to be part of IoT must build in the requisite interface for connectivity and necessary management capability of their data. However, if this functionality is only built-in at the manufacturer level and each manufacturer includes their own unique IoT configurations, it would quickly become a challenge for devices created by different manufacturers to communicate with each other. Introducing standardization protocols for object to object and object to user communication would go a long way toward combating this challenge.

Data exchange protocols

IoT would not be possible without data exchange protocols—a standard set of communication rules. These protocols would provide manufacturers with the necessary targets to make their products compatible with IoT. This not only would make the manufacturers’ jobs easier, but also saves other IoT users from having to operate among multiple interfaces and configurations. Although a single standard protocol for data exchange may not be possible for all IoT candidates, at least few standards must be formulated for various classes of objects.

What are the implications of IoT?

Every new technology comes with associated implications and repercussions. IoT is no exception. Major implications of IoT include:

Increased efficiency

Vehicles in a city could have the ability to communicate with traffic flow sensors. In that case, cars would inform the driver about possible traffic jams and facilitate re-routing.

Retail stores connected to suppliers could automatically pass along the statistics about consumption of products. This would enable the suppliers to quickly replenish popular products.

Such automation and decision-making would increase the efficiency of processes and productivity as a whole.

More accurate statistics

Automated sensors connected to the IoT would have an edge over human beings and manual systems, in terms of timely and accurate data provisioning.

Huge data!

Millions or billions of sensors connected together is an exciting thought, but the estimate of data they would continually generate is astronomical. How that much data will be sifted, selectively stored and then retrieved, is a question which industry has yet to answer.

Security

IoT combines the processing powers and other resources of individual objects for great benefits, but such power must not fall into wrong hands. It is thrilling to think of using IoT to ask a coffee machine to start brewing with your morning alarm clock, but it would be distressing to imagine intruders coming into your house by using IoT to breach your IoT-connected security alarms and gates.

Privacy

A decade ago, organizations used to keep all of their sensitive data on a separate system unconnected to the Internet. Today, organizations are concerned about allowing employees to bring mobile devices, due to their inherent connectivity features. The necessary connectivity of IoT means it will be even harder to keep sensitive data separate and private.

Could anyone explain IoT and its implications?

IoT is the interconnection of many intelligent devices (with sensor or actuator) that can send sensed data back to edge / centralized systems for analytical processing or received control signal from the edge / centralized systems to adjust the device's actuator to influence the environment it is in.

Positive Implications of IoT at higher level include:

• Faster & better decision-making quality - some decision making can be even pre-programmed / automated based on sensors' inputs received at the edge.
• Risk avoidance - with the networking of machines, data & people, triangulated analysis & prediction can be near reality before a problem occurs.
• Lower cost & effective management of entities / environments / products - IoT enables speedier & better quality of monitoring, processing & control as & when needed.

Negative implications of IoT today generally include:

• Lacking security - the end point devices can be hacked & become the sources of security attack into the centralized or other systems.
• Lacking compatibility - IoT consists of a large ecosystem that include many types of products & vendors whereby product standards compatibility can be an issue.
• Complexity - from end point devices to centralized systems via various channels of networking for interconnectedness can be complex that can cause higher cost & longer time of deployment, lower reliability etc. if not design & implement optimally.

IoT can be used across industry verticals including government, manufacturing, Telco, financial services etc.  Attached links include some use cases of IoT at the moment & its future use cases are up to our imagination / further investigation:

http://www.ptc.com/internet-of-things/use-cases

http://www.libelium.com/resources/top_50_iot_sensor_applications_ranking/

http://www.postscapes.com/internet-of-things-examples/