Most clinical encounters lead to a need for information. The first step in EBM is to translate the need for information into a question that can be answered by clinical research.
There are "foreground" questions and "background" questions.
The four parts of an answerable foreground question are PICO:
Questions might investigate: prevention, cost-effectiveness, quality of life, clinical findings, prognosis, aetiology, or therapy, among others. The question asked determines the types of evidence searched.