Companion planting is the practice of planting mutually beneficial species together.
Companion planting - Wikipedia, the free encyclopedia
An example in agriculture would be growing beans on corn. The nitrogen fixed by the bean plant is used by the corn to grow with. The corn plant provides the beans with support to grow up. They both benefit from being grown together.
Examples of this for orchids would be growing spanish moss on your orchids to help maintain a humid microclimate or if your orchids grow better in live moss than dead moss.