Setting Post Image

Hi Everyone,

I’d like to know if there is a way to code any given post so that a specific image will display when a link is created on social sites like Facebook and Twitter.

To be clear, I want the ability to designate the image for displaying on social sites whether or not it is displayed in the post.

I know there is a default image feature but that always displays at the the top of my post. This is not what I’m looking for.

Code is preferred to a plugin but a robust plugin would be ok.

Thanks in advance!!