Malware
Malware, short for malicious software, is any software used to disrupt computer operation, gather sensitive information, or gain access to private computer systems. Malware may be stealthy, intended to steal information or spy on computers without being noticed by the user, or it may be designed to critically damage the system, or to extort payment. 'Malware' is an umbrella term used to refer to a variety of forms of hostile software including computer viruses, worms, Trojan horses, spyware, adware, and other malicious programs. It can take the form of executable code, scripts, active content, and other software. As of 2011 the majority of active malware threats were Trojans rather than viruses, see Figure 1.
Malware is often disguised as, or embedded in, non-malicious files especially executable programs and software installation files. Nowadays, downloading freeware, even from well-known websites, often leads to malware infection because people are unaware of unexpected 'free' contents inside, see Figure 2. Personal data storage devices are also major source of malware spreading, apart from unsecured computer networks. Malware creators always focus their attack on bugs and week points in the systems. It will spread easily and causes wide radius of damage if computers in the network are running on the same version of Operating Systems.
Having antivirus installed in computers is the first key to prevent malware infection, even though they cannot fully protect your computer. Carefully read what is being downloaded from the internet will ensure the safety. Consider using cloud storage or e-mail to secure files instead of portable data storage (flash drives or external hard drives) for more security since almost trustable cloud and e-mail services such as Dropbox, Hotmail, or G-Mail have strong integrated malware detection systems. Using hard drive freezing software such as the Deep Freeze could be the best method to secure your computer, but you need a place to secure your user-created files however. This kind of freezing software will roll back your PC to the initial state at every system restart, deleting all newly-created things including malware. It is better use with cloud storage system for maximum safety and convenience.