Source: Strategic Decisions for Becoming a Multi-Sided Platform: A Case Study (Cia-Christine Korjus).

Multi-sided Platform has following traits:

• enabler of direct interactions between two or more distinct sides
• each sides affiliated with the platform

Affiliation: users on each side make platform specific investments that are necessary in order for them to be able to directly interact with each other.

Multi-sided platform lure at least two customer groups which differ from each other and enable cooperation between those groups.