Digitally signed software refers to programs or applications that have been authenticated using a digital certificate. This certificate, issued by a trusted Certificate Authority (CA), verifies the identity of the software publisher and ensures that the software has not been altered since it was signed. By checking the digital signature, users and operating systems can confirm the legitimacy and integrity of the software before installation. Digitally signed software helps protect users from malicious or tampered programs, reduces the risk of malware infections, and builds trust in the software supply chain.