0 software that tries to make users buy a program, service, etc. by making pop-ups (= small screens that you need to click on to close) appear regularly on their computer screens
It attempts to persuade users to buy the software by displaying ads and other nagware.
Some nagware keeps the message up for a certain time period, forcing the user to wait to continue to use the program.
Feature-limited is merely one mechanism for marketing shareware as a damaged good; others are time-limited, usage-limited, capacity-limited, nagware and output-limited.
