The major use of computer is to store data and for that security is the most important part of the operating system
. A set of well designed and well written security parameter can take care of the security issues in a computer. This security code is hidden within the original code of the OS and works in background.
This is more frequent in windows than other operating systems; mostly against the Mac OS of Apple and Linux. Linux is basically an open source operating system where the users are the developer. The source code is open for anyone interested and for that no one is interested in breaking the code. Instead they develop any leak. And because of hard work of numerous developers around the world, Linux has proven as almost unbreakable OS.
When you connect your computer with the internet, there is a good chance that the stored information is transferred through the web to the person who looks for it. However, it is not very easy to do so and the transported data comes in encrypted format. Windows use a special socket to deliver this type of information called the Secure Socket Layer (SSL). This socket is designed to protect your private information to go out and it will require your permission before the transportation.
So if someone else can get the transferred data in the middle, he wont be able to decode it and find the original meaning. He needs both the key and perfect decoder for that. There is some predefined encryption software in the OS that secure the sensitive files like the system files. You can use a third party application for encrypting other files. There are many of them in the market.
Beside the password, windows use different firewall and antivirus tools for keeping your computer safe. These firewalls monitor each and every command and link that comes to your computer and block the risky ones. After blocking these commands, it will ask for your permission whether they should let them in or not.