In Houdini, you can set up characters using two different styles. The two styles both have advantages and disadvantages, and allow different types of convenience.
|Simple, default style|
The simple style is the style for which Houdini’s UI is optimized: a single end goal for each IK bone chain, and a single IK solver for each bone chain.
|Complex, blended style|
The complex style involves creating multiple goals for a bone chain that live in different spaces (for example, character space and shoulder space for an arm goal) and blending between them based on how the animator wants to pose at any given moment.
The mechanics of setting up bones with this style are described in blending between multiple IK goals .
For another perspective on rigging style, see posing using temporary IK on building a rig without any IK and using Houdini’s temporary IK feature to pose.