What are tertiary buttons?
Tertiary buttons are an optional third style for buttons, these are usually used for actions such as 'cancel' or 'close' actions. They may technically be a button but often they have no background or outline until a user hovers over them, so they simply appear as the label.
What is a primary button?
Primary Buttons
They produce things that didn't exist before. Those are primary actions, or things that we want the user to do as often as possible. Buttons that execute primary actions—primary buttons—should be as visible as possible.
What makes a good button?
Summary. A good button is one that is instinctive to your user — they know what it'll do and where they can find it. The beauty of a button is in its simplicity in function, placement and design. Keep the button text concise and make sure it has enough contrast to other UI elements on the page.