http://afritechnet..co.uk/2015/06/what-is-malware-pt-1-annoying-kind.html

Malware, short for malicious software. It is an umbrella term used to refer to a variety of forms of hostile or intrusive software. Malware is defined by its malicious intent, acting against the requirements of the computer user, and does not include software that causes unintentional harm due to some deficiency. Some malware is destructive by design, others are more of a nuisance but should be seen as a gateway menace in that they may quietly steal data thus leaving the user exposed to further, more devastating, problems:


Adware
Displays unwanted advertising on a computer or mobile device, usually in the form of pop-up ads or redirecting your browser to a specific website - may not cause problems alone, is sometimes bundled with spyware.

Spyware
Installed without the user's knowledge (often accompanies desired freeware or shareware by users), spyware hides within a system and monitors activity - may keep tabs on web browsing and sometimes used to access user emails. Can also be used as a tool to steal username and password information.

Browser Hijacker
Caused by malicious software that redirects a computer’s browser to a predetermined website. Generally used to display advertising, it can also be used to generate visits to a particular website. May direct the user to a malicious website that will download malware onto your computer.

http://afritechnet..com/2015/06/what-is-malware-pt-1-annoying-kind.html

I too agree that malware is very annoying when it gets into the system, so it is very important that you should keep your system safe and free from external threats especially while surfing online. This is the only way to keep your system free from external threats.