Also, you can search in Web of Science and the APPsearch databases.
Nuances -- Boolean, PICO
AND You use AND by default. Intersection of sets. Concussion prevention uses AND function and only gives you results (articles, webpages, etc) that have both words.
OR OR allows you to search synonyms or related (or even unrelated) concepts at the same time. Ankle OR knee OR foot allows you to search all these concepts at one time. For most complex searches use parentheses, (Ankle OR knee OR foot). Carolina OR tennessee OR virginia OR appalach*. Teenager OR adolescent OR youth. Elderly OR aged OR older OR senior. The asterisk searches variations with the same beginning letters.
NOT You probably will not use NOT often. Get rid of unwanted results, if you can identify a word that will work. (Leg OR knee OR thigh) NOT ankle. (I often use Nurs* not "nursing homes.")
Quotation marks are useful, but strictly speaking, are not Boolean.
Helps with creating an answerable, useful question. Helps with choice of search words.
Problem or population -- soccer players
Intervention -- preventive training (or more specific type of preventive training)
Comparison treatment (or placebo) -- alternate type of preventive training? what's being used up to now.
Outcome -- count frequency and severity of injuries. Missed games or training.