The term "area of expertise" refers to a specific field or subject matter in which an individual has gained knowledge, experience and proficiency through study, practice and training. Full definition
Conducted training for parents in areas of expertise including conflict resolution skills, student behavior management, and intervention at home. (jobhero.com)
Keep up with developments in area of expertise by reading current journals, books, or magazine articles. (livecareer.com)
Usually, placing a list of areas of expertise or core skills under the career summary works best. (jobs.telegraph.co.uk)