An operating system is a program that manages the computer hardware. It provides a container environment in which other application programs can work. Malicious software, malware in short, is an umbrella term that covers a variety of forms of hostile or intrusive software. Computer viruses, worms, Trojan horses, ransomware, spyware, adware, and scareware are the examples of malicious software. Proprietary software is software that is owned by an individual or a company (usually the one that developed it). There are almost always major restrictions on its use, and its source code is almost always kept secret. A browser is a software used to connect to the Internet (World Wide Web) and display Web pages. On the other hand, a bug is a computer software that causes incorrect or unexpected results.