There are many antivirus and antimalware software in the market. And Windows Defender, which is built into every Windows 10 PC, is considered to be the bare minimum for securing ones' computer from viruses and malware.

Here, Microsoft wants more than just that. On Thursday, the company announced that Windows Defender has expanded its role, capable of preventing "scareware" optimization apps that warn people of dangers to their PC, tricking them.

Scareware are those malicious computer programs designed to trick a user into buying and downloading unnecessary and potentially dangerous software, such as fake antivirus protection. They prey upon people's fear of being vulnerable by scaring users into upgrading.

Windows isn't perfect, and Windows Defender does have flaws. But if there are apps that vaguely warn of problems with users' PC, then offer to fix them for a price, which can cause more trouble than simply refreshing their PC, Microsoft isn't liking them.

Considering its history, Microsoft never had a good relationship with optimization programs which purport to clean up PC from unwanted junk, potential spyware, and more.

Previously. Microsoft didn't see those apps as unwanted or malicious, and never endorse the use of those tools with Windows. But here, Microsoft wants to block those apps because they don't usually spell out what they did. What Microsoft wants, is preventing its Windows users from paying for something they don't understand.

What's more, those cleaner apps can sometimes mark "innocent" temporary Windows files as issues. This annoyed Microsoft.

To make things clear, Microsoft is cracking them down even further.

Cleaner and optimization apps are welcome, as long as they can explain what they're exactly doing. Microsoft has allowed users to run third-party antivirus app with its Windows Defender simultaneously. So this shouldn't be much of an issue.

But if those apps use "alarming or coercive messages or misleading content to pressure you into paying for additional services or performing superfluous actions," they will be blocked, said Microsoft. Apps that include notices that a paid offer will expire in a limited time, are also affected.

"Customer protection is our top priority," wrote Barak Shein, of the Windows Defender Security Research team, in a blog post. "We adjust, expand, and update our evaluation criteria based on customer feedback and in order to capture the latest developments in unwanted software and other threats."

The Windows software ecosystem has a large variety of software. As the most widely-used OS in a PC, there are people who take advantages of this diversity by selling malicious products that claim to detect and diagnose faults. These programs often offer a free version that purports to find problems and a paid version that can supposedly repair those problems.

And here, Microsoft wants to end that.