This paper was created to give an overview of relevant areas regarding the world-wide shortage of teachers called the teacher gap, provide an insight in its causes and consequences and investigate the role of teacher policy in primary and secondary education, excluding the subsector technical and vocational education and training. In about 40 pages, it tries to systematically compile essential basic knowledge of educational planning with regard to the topic of teachers. Thus it aims to provide an overview to staff who need to become familiar with this topic in a limited timeframe or who are looking for a brief but holistic compendium of the subject matter. Amongst others, this paper is aimed at: educational planners and policymakers in ministries; decision makers in donor and multilateral organizations; researchers and practitioners in development measures.