Does avast protect me from these viruses?
malware, spyware, trojan, computer virus, computer worm, rootkit, ramsomware, and keylogger
viruses, trojans, worm, tootkits, etc are all types of malware.
https://en.wikipedia.org/wiki/Malware
True viruses are hardly seen (if any) for years.
The term anti-virus is for many years a misnomer.
It is a leftover from “the old days” when the only threat came from viruses.
Nowadays “anti malicious activity tool” (or something like that) would be a much better name as the software doesn’t only protect against viruses.
And as I have said many times, security start with the user not with hardware/software.
so does it protect me from malware and all viruses?
sorry i dont speak good english
It protects you from all malware that avast knows of.
Ok thanks 
This might interest you: https://www.avast.com/c-online-threats
Eddy this was very helpful to read in following up my input into the dp.alexa issues.
Do you consider CCleaner would have reported computer misbehaving merely for a file being stored in Avast (maybe in quarantine)?
Might I be correct in thinking that CCleaner decided appropriately it was safe to remove (redundant?) files associated with Avast?
Like your term Malicious Activity Tool - I’ll call them MAT. So I using Avast Premier, CCleaner and Malwarebytes I have three potentially conflicting MATs?
For this “newbie” it seems that these programs to some extent provide different facilities and help
First CCleaner is a Cr4p Cleaner as its name implies, it isn’t looking for suspicious objects, in its Main function it just clears out temporary file locations on your OS and installed programs. Whilst it has other functions, these are the ones of concern to avast users.
I would recommend that you don’t allow CCleaner to clear any Avast locations (so uncheck any avast options in the CCleaner settings). One it could bump into the avast self-defence module, but primarily getting rid of logs and other elements that give you information in the event that you have a problem. Avast also has its own housekeeping function and you can change the avast settings to stop files getting too large.
Some additional links to take a look at, on new technologies in Avast 2017 that help prevent unknown/zero-day threats:
CyberCapture: Protection against zero-second attacks