How to make tag text box

In stackoverflow we can see a text box 'Tags' when we do a post. On typing a word and a space it become a tag. After becoming a tag we cont delete a letter from a word.But we can delete the word itself by clicking on the X image. I want to create a similar text box for tags. In stackoverflow there is auto suggest also associated with this text box but Idon't need that. Any help /link will be appreciated