what is the use of esc_attr() function?

I want to know use of esc_attr()?
how it is used?
Any example would be highly help!

esc_attr( $variable )

esc_attr() is written specifically for escaping a string that is to be used as an html attribute, which means also escaping single and double-quote characters etc.

In general, it’s better to use the data validation API that WP provides rather than the generic PHP functions.