which is better, a 404 error page or redirecting to the front page

[vaskiller]

I was under the impression that 404 redirects to the front page is considered bad. all websites should have a 404 page. But at the same time I notice alot of people in forums that want their site to redirect to front page when a 404 is called. which is better. Having a 404 error page or redirecting to the front page