Database roles

I am not sure if this is the right place for this question or not but here it goes...

I want to add a new user to the database with read-only rights. I know public is selected by default and can not be changed. I also added the user to db_datareader and db_denydatawriter. But just as I was about to save I noticed Read Only. I have done some searching but have not found anything about this role. I assume it does just what it says but I am confused as to why it would be there when I can set the other settings I just did. Is there any benefit to using this role instead of the ones I chose? Should I add this role in addition to the two I have already picked? Any help is greatly appreciated.

thank you,

Kevin

If this is SQL Server 2000, then add them to db_datareader and db_denydatawriter. If this is SQL Server 2005, just grant select permissions on the database to the user.|||If the user is in those fixed database roles then need not worry about setting anything additional, as the user will be in READONLY for data.