Is my computer safe?
There are, of course, degrees of safety when it comes to computing and surfing the Internet, and it greatly depends on what you do on the Internet and what you consider safe. I realize most people want total protection so that bad things won't happen to their computer, but the reality is that it appears to be impossible to completely protect your computer from every sort of attack.
But the good news is that we can do quite a lot to protect your computer. Assuming your on the Internet, there are a few basic protections that can be applied to your system that will give you some peace of mind.
Virus protection is perhaps the most important to Windows users, but it doesn't stop there. Be sure to pick a virus protection software you're comfortable using, but be sure to only install one anti-virus program. Having multiple virus protection software on one machine will cause problems as they interfere with each other, and you'll be less protected with a slow computer as a result.
Spyware (or malware of any kind) can wiggle it's way onto your system quite easily, and it's a good idea to scan for malicious programs one to four times a month with anti-spyware protection. There are a few odd settings that can be tweaked on your computer with software tools designed specifically to help your browser fight back. Mac computers are no exception to getting malware.
What is spyware? Basically spyware is software that gets on your computer to spy on you. Mostly it's used to pickup on your surfing habits so that you can be targeted for advertising, and they can be pretty persistent about getting your habits. Malware is any type of uninvited software that assists itself to your computer and its resources, which mostly just slows your computer down and allows viruses to circumvent your other security protections.
Internet Explorer is notorious for being unsecured (and not following Internet standards), and has since been discontinued by Microsoft. Try a different Internet browser for more secure surfing. (Firefox, Chrome , Brave , and Microsoft Edge )
Then there is the most overall protection any system can have on the Internet; a firewall. There are two types of firewalls, hardware based and software based. The hardware kind is often built right into your router (if you have one), and can be a very effective deterrent. The software kind, though not as effective, installs on your computer and shuts off parts of the internet that people don't usually use. There are millions of ways to get into your computer, and both hardware and software based firewalls prevent nearly every one of the them. It's actually more complicated then that, but it should give you an idea of how useful a firewall can be. (Zone Alarm)
Even if you have zero information on your computer that you care about, hackers and viruses can take advantage of an unsecured computers to assist them in attacking other computers. The hackers can turn your computer into one of their hacking soldiers. They have setup many coordinated attacks that come from unsuspecting home computer users. Your system may have already attacked other computers on the Internet, and you might never know.
Most operating systems these days have at least a basic built-in firewall (software based). If you're behind a hardware firewall, then that should be enough. However, if you're connected to the internet without a hardware firewall, then you really should have a software firewall that is more robust. (Zone Alarm)
The folks at BleepingComputer.com have some great advise on keeping your computer protected.