Is necessary to use clay bar on your cars paint?

I have never heard the term clay bar used outside these internet forums that promote waxing cars. Does the wax cause a problem that makes it necessary to use clay bar when you're cleaning it or is it just detailer hype to make more money?Is necessary to use clay bar on your cars paint?
Clay bars are used by auto detailers on paint that has a rough build up of pollutants on the paint surface. Road tar, factory pollutants, etc. Waxing after clay prep is needed to protect the paint finish. Rub your hand on the paint job, if you don't have a baby *** smooth surface clay may help.Is necessary to use clay bar on your cars paint?
I use a clay bar and soapy water after I have washed my car. I use it to remove over-spray from bridges being painted on the highway. Other than that, there is no real need. You will have to rewash and wax your car after using it. It's a GREAT alternative to buffing to remove over spray. Keep it off the glass!