What is the origin of the idiom "tooth and nail" and when to use it?

The origin of the idiom "tooth and nail" is believed to date back to ancient times when people used their teeth and nails as weapons in physical combat. Today, it is a widely recognized idiom used in both spoken and written English to describe a fierce or vigorous effort to defend or achieve something. It implies a determined and unrelenting struggle, often involving strong resistance or opposition.