Computer Virus’s Malware, short for malicious software

Malware currently causes billions of dollars' worth of economic damage each year, due to causing systems failure, wasting computer resources, corrupting data, increasing maintenance costs, etc. In response, free, open-source antivirus tools have been developed, and an industry of antivirus software has cropped up,

A computer virus is a malware program that, when executed, replicates by inserting copies of itself (possibly modified) into other computer programs, data files, or the boot sector of the hard drive; when this replication succeeds, the affected areas are then said to be "infected’. Viruses often perform some type of harmful activity on infected hosts, such as stealing hard disk space or CPU time, accessing private information, corrupting data, displaying political or humorous messages on the user's screen, spamming their contacts, logging their keystrokes, or even rendering the computer useless. However, not all viruses carry a destructive payload or attempt to hide themselves—the defining characteristic of viruses is that they are self-replicating computer programs which install themselves without user consent.

Spyware is software that aims to gather information about a person or organization without their knowledge and that may send such information to another entity without the consumer's consent, or that asserts control over a computer without the consumer's knowledge.

"Spyware" is mostly classified into four types:

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   System monitors – monitor what you do and where you go
   
2. 
   Trojans, - which disguise itself as something interesting to get you to install or open it
   
3. 
   Adware – software that automatically displays or downloads advertising material (often unwanted) when a user is online.
   
4. 
   tracking cookies – sits in your computer and reports your activity back to its server
   

Whenever spyware is used for malicious purposes, its presence is typically hidden from the user and can be difficult to detect. Some spyware, such as keyloggers, may be installed by the owner of a shared, corporate, or public computer intentionally in order to monitor users. Keyloggers are often used to steal passwords.

While the term spyware suggests software that monitors a user's computing, the functions of spyware can extend beyond simple monitoring. Spyware can collect almost any type of data, including personal information like internet surfing habits, user logins, and bank or credit account information. Spyware can also interfere with user control of a computer by installing additional software or redirecting web browsers. Some spyware can change computer settings, which can result in slow Internet connection speeds, un-authorized changes in browser settings, or changes to software settings.

Sometimes, spyware is included along with genuine software, and may come from a malicious website. In response to the emergence of spyware, a small industry has sprung up dealing in anti-spyware software. Running anti-spyware software has become a widely recognized element of computer security practices. A number of jurisdictions have passed anti-spyware laws, which usually target any software that is surreptitiously installed to control a user's computer.

A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers. Often, it uses a computer network to spread itself, relying on security failures on the target computer to access it. Unlike a computer virus, it does not need to attach itself to an existing program. Worms almost always cause at least some harm to the network, even if only by consuming bandwidth, whereas viruses almost always corrupt or modify files on a targeted computer.
Scareware is a form of malicious software that uses social engineering to cause shock, anxiety, or the perception of a threat in order to manipulate users into buying unwanted software. For example: You get a message saying you have a virus that can severely damage your hard drive and to “click here” Then they will try to sell you a fake antivirus to remove it.
Here's another unwelcome possibility. If the bad guys manage to infest your PC with malware called phishing that gathers passwords and personal information, they might well parlay that data into full-blown identity theft. You might not know a thing about it until you get the bill for a credit card account you never opened, or find that there's a lien on your house.
Antivirus programs

Antivirus software are programs that help protect your computer against most viruses, worms, Trojan horses, and other unwanted invaders that can make your computer "sick."

There are many dangers lurking on the Internet. And a savvy web surfer and searcher knows that there’s ways to protect themselves. Here are some tips to keep you safe while you surf the internet.

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  Keep security software current: Having the latest security software, web browser, and operating system are the best defenses against viruses, malware, and other online threats.
  
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  Automate software updates: Many software programs will automatically connect and update to defend against known risks. Turn on automatic updates if that’s an available option.
  
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  Protect all devices that connect to the Internet: Along with computers, smart phones, gaming systems, and other web-enabled devices also need protection from viruses and malware.
  
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  Plug & scan: “USBs” and other external devices can be infected by viruses and malware. Use your security software to scan them.
  

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  Secure your accounts: Ask for protection beyond passwords. Many account providers now offer additional ways for you verify who you are before you conduct business on that site.
  
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  Make passwords long and strong: Combine capital and lowercase letters with numbers and symbols to create a more secure password.
  
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  Unique account, unique password: Separate passwords for every account helps to thwart cybercriminals.
  
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  Write it down and keep it safe: Everyone can forget a password. Keep a list that’s stored in a safe, secure place away from your computer or use a password lock program.
  
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  Own your online presence: When available, set the privacy and security settings on websites to your comfort level for information sharing. It’s ok to limit who you share information with.
  

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  When in doubt, throw it out: Links in email, tweets, posts, and online advertising are often the way cybercriminals compromise your computer. If it looks suspicious, even if you know the source, it’s best to delete or if appropriate, mark as junk email.
  
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  Get savvy about Wi-Fi hotspots: Limit the type of business you conduct and adjust the security settings on your device to limit who can access your machine.
  
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  Protect your money: When banking and shopping, check to be sure the sites is security enabled. Look for web addresses with “https://” or “shttp://”, which means the site takes extra measures to help secure your information. “ Http://” is not secure. (Hypertext Transfer Protocol)
  

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  Stay current. Keep pace with new ways to stay safe online: Check trusted websites for the latest information, and share with friends, family, and colleagues and encourage them to be web wise.
  
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  Think before you act: Be wary of communications that implores you to act immediately, offers something that sounds too good to be true, or asks for personal information.
  
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  Back it up: Protect your valuable work, music, photos, and other digital information by making an electronic copy and storing it safely.
  
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  Use your noggin. You do not need to be a seasoned computer whiz to know that it’s not smart to open an attachment titled, “Claim Your Inheritance!” Using common sense while surfing the Web can protect you from some hungry cyber-shark.
  
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  Shop safely. Check them out before you place your order. Don’t shop on a site unless it has the “https” and a padlock icon to the left or right of the URL. Also, protect yourself and use PayPal instead of a credit or debit card while shopping online—a credit card company is more likely to reimburse you for fraudulent charges.
  
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  Know the scams. Read articles and blogs, follow the news, and share information so you can learn about different kinds of scams and what you can do to avoid them.
  

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  Safer for me more secure for all: What you do online has the potential to affect everyone – at home, at work and around the world. Practicing good online habits benefits the global digital community.
  
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  Post only about others as you have them post about you.
  
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  Help the authorities fight cybercrime: Report stolen finances or identities and other cybercrime to your local law enforcement.