Frameworks help researchers structure a research question and clarify search concepts. There are many different frameworks depending on the type of question. For clinical questions, the most well-known is PICO. Sometimes your question may not fit perfectly into a framework. You can use part of a framework if necessary.
More details about alternative frameworks are available here.
(for questions covering the effectiveness of an intervention, treatment etc.)
Patient, Population or Problem - who is the patient and/or what is the problem?
Intervention - what intervention is being considered?
Comparison - what intervention is this being compared with (a comparison is not always necessary)
Outcomes - what do you hope to accomplish, improve or affect?
Example: Alternatives to drugs for controlling headaches in children
There are extensions to the PICO framework available which you can use if your topic has additional concepts: