Select
Selects let users choose a single option from a dropdown list. They conserve space by hiding options until activated. Use selects when you have 4+ options that would take too much space as radio buttons.
Usage Guidelines
Do
Use Select for lists of 4+ options where only one can be chosen.
Don't
Don't use Select for 2-3 options. Radio buttons are faster and show all choices at once.
Do
Provide a meaningful placeholder that describes what the user should select.
Don't
Don't use 'Select...' as placeholder. Be specific: 'Select a category', 'Choose your role'.