antivirus programs

Antivirus (AV) programs have always been controversial. No such thing as the best, perhaps the best for a very short period of time as new virus/malwares are popping up constantly...

What you are looking for is one that consistently ranks high, especially with viruses 'in the wild', updates often, runs in the background, uses minimal resources and has easy user interface (set and forget for home users)...

A virus in the wild is a real virus, one that has been deployed in the real world. Most updates are merely potential virus, they could be a virus if a bad guy made it and successfully deployed. The AV developers discover what could be and make an update, sort of like a vaccine...

The difference between free and paid are often merely 'features' as they don't spend time and resources to make from scratch an AV that they are going to give away... :S They often have ads or nagging messages to buy the pro version as a means of income and for many users, it puts them on a guilt trip to buy after using the free version...

1492 has given you a great AV comparison site, and I'll give you another:
av-comparatives.org
Spend a few hours learning as the best security is knowledge...

Basic things to do:

Install a consistently high ranking AV program of your choice (Many companies share their AV info/definitions as it makes good financial sense...)

For example, Kaspersky was highly respected, however last year some former employees spilled the beans on some tactics that they were doing...or potentially doing, depending on who you want to believe, former employees or the Russian founder, ex-KGB schooled, Eugene Kaspersky.
https://en.wikipedia.org/wiki/Kaspersky_Lab
http://www.reuters.com/article/us-kaspersky-rivals-idUSKCN0QJ1CR20150814

Others have played similar games, after all it's business...

Personally, I wouldn't trust Norton/Symantec or McAfee with anything for home computers. Enterprise versions are a bit different. Their histories are too shady, at best... (Although some of my IT friends like to use Norton’s ConnectSafe DNS server)

Neither Microsoft (MS) nor Windows will tell you via a pop up that you have malware, virus, etc. If a pop up tells you this, open task manager and end/close your browser immediately(Alt+F4 will work sometimes), clean temp files and reboot. Do not click on the pop up or call the phone number…
Only your AV or anti-malware program will detect things such as that... NOT MS or Windows...

Using a good, ‘on demand’ anti-malware program, such as Malwarebytes and some others, on occasion, definitely when you have suspicious things going on with your computer. (See below on download sites.)

NEVER run 2 active AV programs at the same time. Just by nature of what/how they work, ...DON’T do it...

Clean your temp files and such, often after web surfing and especially before you reboot as nasties often hide and wait for a reboot to activate. CCleaner by Piriform is quick and handy for that.

No single program can do everything. No different than expecting penicillin to cure everything. Once infected, expect to use 4 or 5 programs to clean all traces or expect a remanifestation later, especially after a reboot... (I am really not enthusiastic about giving the names of programs anymore as if you are knowledgeable you can find the programs and if not, ...well you may be best off to ask a friend or pay a professional...)

Downloading and Download Sites

Remember to be very careful where you download programs from as many have taken to adding undesirables into the programs. Some formerly trusted places now routinely do that, such as CNET and others.
Also be careful that you click on the correct link for the correct program as many sites will try and confuse you. They will put a program with a similar name to what you want or hide the link so you click on something else…
I always try to go to the actual programmer’s site, not a download site that hosts many programs…

Be sure to search and read reviews on any program that you are contemplating. Search terms such as; ‘program name’ malware, ‘program name’ reviews and such...

ALWAYS read the EULA- End User License Agreement, when installing a program. You will be surprised what they tell you… Many people just click ‘yes’ or ‘ok’ and are totally clueless to what they are giving permission to share (think spam) or what the program will do...

Have another user account and don't surf using an administrator account...

Use a router or better yet, a UTM hardware firewall, if you have some extra cash and feel that your data, bank info and such are worth protecting...

You may consider using “Safe DNS services” such as Open DNS. Search and learn...

Keep your operating system and other programs (if you use them, Adobe, Java, etc.) up to date

Use an ad blocker

As with MS operating systems, Internet Explorer is a target due to being the most used in the world. The bad guys go after quantity…unless they specifically target...
You may want to use a different browser

Chrome by Google has a sandbox feature which is very good, however I am becoming afraid of Google and the massive amount of info they have stored on everyone... Your call...

This post/thread is mainly about free AV products and computer internet security in general. Pay AV's are all about features, such as deploying to many machines at one time from a server, and such...

Remember, if someone has physical access to your computer, it's not your computer anymore...

And computer security is like putting 10 dead bolts on your doors at home, when you open the door and ask, "who is it"?, you have no security anymore...same thing with your browser...

Just some things to think about. There is no substitute for knowledge. A false sense of security is what many run with...
Fools rush in where angels fear to tread...

Stay safe in cyberspace!