[hechshers.info](http://www.hechshers.info/shapes/0900-0999.htm#END) provides information about known hechshers. [This page](http://www.hechshers.info/logos/index.htm) records information about logos which are not hechshers. For example  one is said to be a commercial trademark. 

There needs to be a hechsher recording supervision from an authority which you recognise and trust.