Vanity metrics are those product development metrics that make us feel good, but don't necessarily translate into real success. They're the things we can easily measure and track, but that don't necessarily tell us whether our product is actually being used or whether it's making a difference in people's lives. Examples of vanity metrics include things like pageviews, installations, and sign-ups. These are all important numbers to track, but they don't necessarily give us a complete picture of whether our product is truly being successful. The challenge with vanity metrics is that they can often be misleading; they can give us a false sense of progress and success, when in reality our product might not be performing as well as we think. It's important to be aware of vanity metrics and to put them into context; they can be useful indicators of progress, but they should never be used as the sole measure of success.