I use Avast as my antivirus. Yesterday while using my system, an Avast popup came up saying 'a suspicious rootkit has been found'. Avast suggested to delete it and I did so. Normally when Avast finds a virus, it recommends to fix the issue automatically. But in this case it recommended to delete the rootkit.
So, what is a rootkit ? I have heard about virus, malware, spyware, trojan etc. But rootkit is new to me.