This video tutorial is an introduction to using attributes and local variables in Houdini. It covers:
Different types of attribute: vertex, point, primitive and detail;
When attributes and variables can be used, and when not;
Vector vs 3 value float attributes;
Converting between point and detail attributes etc.
This first part of the video tutorial looks at using the foreach sop to iterate over groups of primitives, using the example of creating balconies on a set of primitives.