Convenience is anything that is intened to save a time, energy or frustration. A convenience store at a petrol station, for example, sells items that have nothing to do with gasoline/petrol, but it saves the consumer from having to go to a grocery store. "Convenience" is a very relative term and its meaning tends to change over time. What was once a convenience (eg. an automobile) is today regarded as a normal part of life. Likewise today's luxuries may be perceived in the same way in the future.