Smartphones are vulnerable to malware and can show signs of infection, such as increased data usage, slower performance, unexpected pop-ups, reduced battery life, overheating, and unfamiliar charges. Common sources of malware include clicking on malicious links, downloading questionable apps, and connecting to public Wi-Fi. It is recommended to use antivirus software for enhanced protection, as smartphones have basic security features but can benefit from additional measures. TotalAV is suggested as a comprehensive antivirus solution that protects multiple devices, improves performance, blocks untrustworthy websites, and provides firewall protection. Currently, TotalAV is offering a discount for its services.