People are more likely to pay attention to advertising if it is relevant to their current needs or desires. For example, as young, urban professionals emerge from the subway after work, they often think about the evening ahead. This is an ideal moment to advertise a low alcohol beer.

Technology can now enable ads to be served to people for whom the message is highly relevant at that moment. For example, ads for train services can be delivered to drivers who have just had a difficult journey to work, ads for waterproof jackets to people caught outdoors in the rain and ads for home security systems to people who have just watched the news.