How to block someone on Facebook?

[Leo]

I don't want to unfriend a friend on face book, but I don't want him to see my updates.

[Daniel]

While signed into your facebook acc head to the settings (top right) and then click on privacy settings. Then where it says "Who can see future posts" click edit and then in the drop down menu click custom. Next in the "These people or lists" box start typing their name and they should pop up. Click their name, then press save changes. Facebook never reveals when you choose not to share a post with somebody.