Getting table set up for comments

I am working on a project that lets visitors to my webpage post comments. I have there name, city, etc. stored into an sql database. This all works until I put text into the comments field of my form. I get this message when it is trying execute -- String or binary data would be truncated. I was wondering what data type to use, I have used char and varchar and neither one is working. Is there anything else I could try to fix this.Try Text data type if it is more than 8000 characters.