We may think that worms, Trojans, spyware, adware, viruses and other types of malware are all the same. But we are pretty much wrong here. Here is an overview of how they differ from each other.
Worms: Worms are standalone programs that create their own copies and spread to computers via network. Worms do not require hosts (programs or files to attach themselves to). Most of the times, these worms cause security problems to network, in any way they can. Worms are responsible for creating backdoors in infected computers, converting them to zombie systems for either sending spam e-mails or cloaking addresses etc.
Trojans: Trojans do not replicate themselves. This is the biggest difference between Trojans and worms/viruses. These malicious programs do not infect other files on a computer. Instead, they simply work to gain access to operating system, setting up a backdoor and may be used to steal vital information from the computer. Most often, these programs come from internet or via online games. One may download them thinking they are additional gifts or free goodies with something that they may have bought or downloaded.
Viruses: Viruses are self-replicating programs that require a host to get attached to and once the file or program is infected, the virus continues to create its copies and infect more and more files, causing damage like altering, modifying or deleting files, crashing computers or infect operating systems as well as antivirus systems at times. Sometimes, viruses may have no other task than replicating themselves and spreading more.
Spyware: Spyware is a type of malware that gathers information about organizations or a person while they may not know anything about it. This particular malware is divided into four types. Adware, system monitors, tracking cookies and Trojans. Information extracted includes credit or banking details, user logins or internet surfing habits. This type of sensitive information can be used by bad people for causing damage to you financially or socially too.
Adware: A software that works as a package for automatically rendering ads for generation of revenue for its creator. These ads may be in some form of user interface coupled with the software or may pop during installation of nay software on your computer system. These ads are mostly categorized as unwanted ads and hence termed as adware.
Other types of malware: There are many different types of malware than those mentioned above. It may include keyloggers, rootkits, ransomware, rogue security software, dialers or malicious BHOs etc. The main purpose of these types of malware is to disrupt smooth functioning of a computer system. Furthermore, these malwares may be employed for gathering sensitive information. If not, then these can be used for gaining access private PC systems.
For prevention of potential attacks from such malware and viruses, anti-malware and antivirus software are employed in computer systems. These programs are responsible for blocking threats or detecting and then successfully removing them from a computer system. Such a system runs smooth and stays secure from these types of threats.