 Your Mac suddenly becomes slow in everyday use, as it can be possible that there is some software running in the background is taking up resources.  You will see that there is a new toolbar in your browser that didn't install. Typically these toolbars claim to make it easier to search or shop.  There will any web searches that get redirected suddenly without any information from your usual search engine to some site you've never heard of.  All web pages are covered with adverts.

The Malware looks legitimate software like a virus scanner that you download in panic after believing that your Mac is infected. Here, check for the reviews of the apps and ask for the personal recommendations from others in order to prevent downloading the unusual apps.

Most of the time, malware or viruses can be hidden in the form of image files, word processing or PDF document that you open without knowing the actual aim of them. Feasibly upon finding a strange new file on your desktop, make sure you do not open that. The malware creator’s method here is simply to give the malware a fake file extension

In addition, virus and malware also get onto your Mac through a flaw or the security hole in your browser you are working on. For instance, the word processor or the PDF viewer, it these cases, the ordinary webpage or the document you open might contain the hidden virus and malware that runs without your knowledge and information.