What are evidence-based interventions (EBI)?

What exactly are evidence-based interventions, or EBI's, and how do they differ from traditional methods of treatment? Are there specific criteria that must be met in order for an intervention to be considered evidence-based? How do researchers determine the effectiveness of these interventions, and what kind of data is typically used to support their conclusions? Finally, are there any potential limitations or drawbacks to relying solely on evidence-based interventions?