A smart tip is a small user interface element that prompts users to take specific actions. They can appear as small pieces of text that are triggered when a user hovers or clicks on a button.
When done well, smart tips are unobtrusive and only arise when the user needs help learning to use a piece of software. Additionally, they have utility in explaining to users or refreshing them about lesser-used functions.
Developers shouldn't use smart tips as a crutch to cover over a poor UI. They work best as short, punchy instructions that don't break the user's flow.