Softwares are like a "bridge" linking two different programs and hardware. The provide a platform through which different programs or hardware components can communicate with each other in a common "language" they will all understand.
In order to have something in computer you need to put that there. The process is called installation.
A new computer is like a man who lost his memory. He can understand if we remind him. For example, when we install a software of a video player. Now computer got his memory back "Oh yes yes I know it. I can do it. I know how to play and how to stop. I have done it before and now I remember it completely". Then it shows the video on monitor and send sounds through speakers.
If you install a calculation software same thing happens. It remembers every thing related to calculations. How to plus, how to minus and how to multiply and divide. So it actually get that memory from the codes inside that software.
It is same like that, when we meet with our childhood friend who forgot you. When we memorize him from different aspects, Locations and known things or people then he would remember and identify you.
So the computer software is same like this in easy and simple words. I hope you will understand my point and got the idea that why software needs to install.
There are appliances [e.g. toaster, external hard drive] that do not need software. There are devices [e.g. computers, video games, smart phones, tablets] that require you install software to get value from the device. Without software the device is "dumb", but when you "install software" you make it "smart". Often you can perform specialized tasks with a smart device and the right installed software! Together appliances and devices help us through our daily activities as individuals and small businesses.
For some applications the trend is moving away from you having to purchase the software then be responsible for installing it and also keeping it up to date on computer(s) that you own in order to use it.
The software as a service model is you pay a monthly or annual or perhaps one-time fee to use the software from another computer that you access over the internet usually through your web browser. Either the vendor or a service company maintains the software for you and the fee you pay is then split between the development of the software and maintaining it on the computer(s) where you are accessing it.
Software needs to be installed on a computer, rather than copied because there are files that link the software files to the operating system so they can communicate. The operating system and software have to do some introductions to each other to sync all of the different processes, This usually happens with the.DLL files, The system files and the registry on a Windows machine.Mac's will be similar in process but may be named differently.
software that needs to be installed, basically needs to apply proper file locations, system setup files, as well as primarily setting up registery keys to certify the existance of the application.
OK, lets keep this pretty simple. Think of a computer like you would an automobile. A computer is a structure made up of parts. When the parts are related or dependent in function, you can label it a system. A car is a system. Motor, transmission, body, tires, etc, all working together. In order for this system of disparate parts to function smoothly and to move you from one point to another, there must be something that commands those disparate pieces to move in unison. In a car, that is the driver. A computer is something like that with different parts in a system. What makes the various parts of a computer work together is a string of commands that are structured so that every piece does what is required at exactly the moment it is needed to perform something like printing a document, placing a dot on a screen or sending a note to a speaker. That string of commands is called a program and because it is not a structure of nuts and bolts, it is called software.
Software coordinates the actions of your computer hardware so that it works together to perform a task or a series of tasks.
That was pretty simplistic. I hope I didn't make it too simple. If you need a more complex explanation, get back to me and we can go where ever you want to go. Just give me some guidance as to your desired level of information.
As a Laymen. If we perceive as our-self as machines, so we need to learn or do course for information to process. Until we don't know how, what and when to process, we would be just junk machines. So, goes for the Computer hardware (as body), Electricity (as soul) and Software (as mind to store and process information). No mind and soul, we would be buried or burnt. Same goes for Computers or any Machine(s). I hope you get the answer.
Software is a set of instructions that perform a task. This set of instructions (software program) must reside in the computer for it to do what it supposed to do when you want it.