The term training refers to the acquisition of knowlege, skills, and competencies as a result of the teaching of vocational or practical skills and knowledge that relate to specific useful competencies. It forms the core of apprenticeships and provides the backbone of content at technical colleges and polytechnics. In addition to the basic training required for a trade, occupation or profession, observers of the labor-market[who?] recognise today the need to continue training beyond initial qualifications: to maintain, upgrade and update skills throughout working life. People within many professions and occupations may refer to this sort of training as professional development.