An alert type.
An accordion type.
The message displayed below the button.
If you click the button again, the message disappears.
A modal window type.
If you click the button, the screen gets dark and the message display at the middle of the screen.
If you click the part of dark, back to normal screen.
Button-1: Alert Type
The most simple way to display a message.
Button-2: Accordion Type
Set the message below the button and it can be appeared and disappeared clicking the button.
You can also make an accordion menu with this way.
Button-3: Modal Window Type
Set the dark screen layer(mask) and the message window and these can be appeared and disappeared clicking the button.
This way is called “modal window” generally.