Quick scan: scans the main drive of your PC where system files are stored, auto-start programs, and all known types of rootkits.
Full Virus Scan: a predefined, in-depth scan of your system that checks your storage drives and memory for malware (including rootkits).
Smart Scan: a comprehensive scan that detects malware, out-of-date software, browser add-ons with poor reputations, network threats, performance issues, and passwords that are weak, duplicated, or compromised.
In addition to Antivirus shields, Avast Antivirus includes the following scans: Refer to the following sections for details about Antivirus scans: You can also create your own scan with parameters specified by you. Avast Antivirus provides a range of scans to protect your PC from malware.