How to reuse a class in sass without using a mixin? [duplicate]

I want all my anchors in my application look like .btn (Twitter Bootstrap class), is there a way to make this?

I did

a{   @include btn; }

but it does not work because btn should be a mixin, and it's a Twitter Bootstrap class.

What is the difference between mixin and extend in Sass?

@mixin is used to group css code that has to be reused a no of times. Whereas the @extend is used in SASS to inherit(share) the properties from another css selector. @extend is most useful when the elements are almost same or identical. The main difference between the two is in their compiled CSS file.

You want to use @extend .btn; - @extend allows you to inherit all the properties of a selector without having to define it as a mixin.