NANO AntiVirus is a new security product made in Russia. It has a major advantage of being free and pretty easy to use.
It offers basic protection against all kinds of threats, like worms, viruses, trojans, backdoors, spyware and adware.
It's pretty configurable and offers both realtime protection for local drives: HDD, USB devices and website protection (Web Guard module) against any malware trying to infect your PC while browsing the internet.
On-demand scanner offers several quick options like Complete system scan, Express system test (scanning memory, boot sectors, registry) and Media test for removable drives like CDDVD and USB devices.
This program resides in the memory and either alerts when something suspicious is found or quarantines it automatically and you will be able to see each action in the Event log recorded.
It does not incorporate cloud scanning or behavioral detection as some other major products, but offers decent protection using the classic method of signatures and a good heuristic engine for detecting new and unknown threats.