Which kind of application makes use of a PKI?

Public Key Infrastructure (PKI) is essential for securing digital communications and transactions, primarily by using cryptography to ensure confidentiality, integrity, and authenticity. Web browsers utilize PKI to establish secure connections over the internet, particularly through the HTTPS protocol, which is crucial for online banking, shopping, and any situation where sensitive data is exchanged.

In a web browser, PKI works by employing digital certificates that authenticate the identities of websites, enabling users to trust that they are communicating with legitimate entities. Browsers check these certificates against Certificate Authorities, which are part of the PKI framework, to validate their authenticity and establish a secure communication channel.

The other options, such as spreadsheet applications, graphic design software, and database management systems, do not primarily focus on secure web-based transactions in the same way that web browsers do. While they may have security features, they usually do not incorporate PKI for secure communications, making the use of PKI specifically relevant to web browsers for secure transactions.