Code Signing is a method of using an X.509 certificate to place a digital signature on a file, program, or software update which guarantees that the file or software has not been tampered with or compromised. It’s a means of providing an added level of assurance to the user that the item is authentic and safe to use. 

Software developers digitally sign their software programs, apps, and drivers,  with code signing certificates to prevent tampering or compromise of applications by unauthorized parties.

These digital certificates are especially useful in applications that are distributed through the Internet, where applications can pass through a number of suspicious parties or websites before it finally gets downloaded and installed.

Unsigned applications can easily be altered to include malware or viruses, and these untrusted applications will display warning messages resulting in lower installation yields. A code signing certificate issued from a trusted Certificate Authority such as SSL.com can prevent all of those problems.