just going through some slides for SharePoint 2010 Developer Certification slides and it says Site Columns are related to web, but I thought they are created on site collection level, can someone explain the concept of it for me please.
Have a look @ Introduction to Columns
Specially look at the Column Scope section, which says Site Columns scope is same as Content Types...!
I hope this explains...
SharePoint also offers you the possibility to create Site Columns. What are these? They are columns that we create in a SharePoint site to be available to its’ sub sites.
SharePoint Columns, Site Columns and Content Types explained As you can see when you create a SharePoint Site Column it is available to the site and its’ sub-sites. This makes it very interesting for us to reuse a configuration.
For more info see