Operating systems are the set of programs. It can manage computer hardware resources. It provides services for application software. It is the most common type of system software. Time sharing operating systems are more efficient. It is used for accounting such as processor time, printing, mass storage and many more resources. The operating systems are an important role between the computer hardware and the application programs. Operating systems are found in cellular phones, video game consoles, super computers and web servers. Some of the modern operating systems include Linux, Android, iOS and many more. There are many types of operating systems available such as real time operating system, multi tasking operating system, multi user operating system, distributed and embedded operating systems. It consists of many parts. The main component of operating system is kernel. It is used to control low level processes. Digital Equipment Corporation is developed in many operating systems.

Hardware is the component devices. It can be installed in computer case. Operating system is used to support for application software. Operating systems are used to communicate with devices of hardware buses and device drivers. Mother board is the main component in hardware. Some of the other parts of computer include the RAM and the CPU. Some of the components are included in the motherboard. The power supply unit is used to convert electric power to low voltage DC power. Some of the hardware components in personal computer are disk drives, disks, keyboards, display screens, printers, chips, boards and many more. The business of computer hardware is more profitable. There are many different types of components included in the computer hardware. Motherboard is the most important component of a computer. Both hardware and software is also essential part of computer. You can use better hardware software in your personal computers.

Internet is the global system. It is interconnected computer networks. It includes network of networks. It consists of private, public, academic, government networks and business. Internet is used to get more information resources and services. Some of the traditional communications media is music, film, telephone, television and many more. In these days, most of the people like to buy in online shopping. It is used for many purposes such as businesses, financial services, online shopping, instant messaging and many more. There are many social networking sites available. Internetwork is the abbreviation of the internet. Internet is simply known as the net. The global network is used in computers. In this service, there are many countries exchange their news, data and opinions. There is little difference between the Internet and the World Wide Web. Internet advertising is more popular in these days. It is more cost effective. It provides many applications.

IPad is a tablet computer. It is designed and developed by Apple Company. It provides audio- visual media such as books, movies, music, games and web content. It was implemented by January 27, 2010. It is controlled by multi- touch display. It is used for Wi- Fi connection.  The company of Apple releases the first iPad in April, 2010. It is more popular in all over the world. The first tablet computer was introduced in 1993 namely the Newton MessagePad 100. Apple iPad accessories are more fascinating. The Apple company was launched the new product. iPad keyboard is also known as Keyboard Dock. iPad cases are the perfect way to keep your iPad. Apple wireless keyboard is made with Bluetooth based technology. It comes in thin and sleek dimensions. Apple accessories are very convenient and clear way to hear music. It comes with a wireless remote and mic. The remote is used to control volume of music.

Electronic mail is also known as e- mail. It is used for exchanging digital messages from one person to more recipients. Email services are operated on the Internet or many computer networks. Email service is used for instant messaging. Email services are accepting forward, deliver and store messages. E- Mail message includes three components such as the message envelope, the message header and the message body. The header of message includes control information like email address of one or more recipients. The electronic mail is the transmission of messages through communication networks. The messages are entered from the keyboard. In this service, you can send messages more than one person at the same time. Many of the e- mail systems include text editor and it is used for composing messages. These types of services are called as broadcasting. Any kind of business need email service. Email marketing is more popular in these days and it is more cost effective.

Online communication is a great achievement of the modern world. It includes various aspects. Online communication consists of many things such as from emails and online chats to video conferencing and web conferencing. Chats and emails help to communicate with people. You can get lot of new friends through this online communication. Video conferencing online communication provides many applications and advantages. Video conferencing is used for meetings in corporate offices. It is one special kind of online communication. It is done by video conferencing software. It is integrated with video chat facilities. It is used for job training sessions, product demonstrations, explanatory sessions and PowerPoint presentations. It comes with the whiteboard facilities. It is more comprehensible. It permits remote desktop sharing facility. Online communications makes the interaction process easily. You can communicate with a greater speed. It is more effective communication. It only needs proper organization. It is available on the market in these days.

In these days, mobile phones are one of the most essential devices. It is also known as cellular phone, cell phone and a hand phone. It is used to make and receive telephone calls through radio link. The cell phone network is provided by a mobile phone operator. The modern mobile phones are used for many purposes such as sending text messages, email, MMS, short range wireless communications like infrared, Bluetooth, internet access, business applications, gaming and photography. The mobile phone has general computing capabilities. It is also referred to as smart phones. The first cellular phone device was implemented by Dr. Martin Cooper of Motorola in 1973. The mobile phones provide many features. It is made with an innovative technology. The battery is the power source of the phone functions. It is also used for sending text messaging. It is simply known as SMS. SIM card is another essential part of mobile phones.

GSM stands for Global System for Mobile Communications. It is developed by the European Telecommunications Standards Institute. It is a second generation digital cellular network. It is a one kind of cellular network. It has different cell sizes of a GSM networks such as pico, macro, micro, femto and umbrella cells. Macro cells are based on the base station antenna. Micro cells are installed in average roof top level. It is used in urban areas. Picocells are small cells. Femtocells are cells and it is designed for residential or small business environments. Umbrella cells are used in shadowed regions. The radius of the cell varies from the antenna height, propagation conditions and antenna gain. The cell radius varies depending on the antenna system. GSM services are provided for indoor coverage. GSM is used for variety of voice codes. It was enhanced in 1997. The network structure is based on the base station, switching sub system and operation support system.

SIM is abbreviated as a subscriber identity module or subscriber identification module. It is an integrated circuit. It is a key and used to find the subscribers on mobile telephone devices. The main work of SIM card is transferred between various mobile devices. SIM card has unique serial number. It is used for security authentication, temporary information, ciphering information and related to the local network. SIM number is unique. You can give two passwords namely a personal identification number is used for ordinary use and a personal unblocking code is used for PIN unlocking. SIM card was made in 1991. There are three operating voltages SIM cards available such as 5 V, 3 V and 1.8 V. The operating voltage of the first SIM cards was established in 1998. SIM card is available in two types such as GSM and CDMA. SIM cards are used for making phone calls and sending messages.