# Core Classes

- [Classes](/xoops-modules-cookbook/core-classes/core.md)
- [Key Classes](/xoops-modules-cookbook/core-classes/core/key-classes.md)
- [Helper Class](/xoops-modules-cookbook/core-classes/core/helper-class.md)
- [Criteria](/xoops-modules-cookbook/core-classes/core/criteria.md)
- [XoopsObject](/xoops-modules-cookbook/core-classes/core/xoopsobject.md)
- [XoopsObject & XoopsObjectHandler](/xoops-modules-cookbook/core-classes/core/xoopsobjectandhandler.md)
- [XoopsObjectHandler & XoopsPersistableObjectHandler](/xoops-modules-cookbook/core-classes/core/xoopspersistableobjecthandler.md)