Teachers' salaries are the average gross salaries of educational personnel according to official pay scales, before the deduction of taxes, including the employee's contributions for retirement or health care plans, and other contributions or premiums for social insurance or other purposes, but less the employer’s contribution to social security and pension. Salaries based on the most prevalent qualifications are shown in USD covering early childhood education teachers, primary and secondary teachers at the beginning of their career, after 15 years, and at the top of the scale. Trends in salaries are shown as an index with base year 2010.

The ratio of students per teaching staff is the total number of full-time equivalent students enrolled at a specific level of education divided by the total number of full-time equivalent teachers at the same level. Teachers refer to professional personnel directly involved in teaching students: classroom teachers, special education teachers and other teachers who work with students as a whole class in a classroom, in small groups in a resource room, or in one-to-one teaching inside or outside a regular classroom. This does not include teachers’ aides and other paraprofessional personnel.

Women teachers are women whose professional activity is student instruction, involving the delivery of lessons to students.

A teacher is a person whose professional activity involves the planning, organising and conducting of group activities to develop students’ knowledge, skills and attitudes as stipulated by educational programmes. Teachers may work with students as a whole class, in small groups or one-to-one, inside or outside regular classrooms. In this indicator, teachers are compared by their average age and work experience measured in years. Teachers do not include non-professional personnel who support teachers in providing instruction to students, such as teachers’ aides and other paraprofessional personnel.

This indicator presents preparation time and statutory teaching time. Teaching time is the number of hours spent teaching a group or class of students according to the formal policy in the country; preparation time is the time spent preparing for teaching. For pre-primary, primary, lower secondary and upper secondary schools, teaching time is presented in hours per year. For lower secondary schools, both teaching time and preparation time are shown in hours per week.

Teaching staff include professional personnel directly involved in teaching students, including classroom teachers, special education teachers and other teachers who work with students as a whole class, in small groups, or in one-to-one teaching. Teaching staff also include department chairs of whose duties include some teaching, but it does not include non-professional personnel who support teachers in providing instruction to students, such as teachers’ aides and other paraprofessional personnel. Academic staff include personnel whose primary assignment is instruction, research or public service, holding an academic rank with such titles as professor, associate professor, assistant professor, instructor, lecturer, or the equivalent of any of these academic ranks. The category includes personnel with other titles (e.g. dean, director, associate dean, assistant dean, chair or head of department), if their principal activity is instruction or research.

School principals are the link between teachers, students and their parents or guardians, the education system and the wider community. Principals may contribute to student achievement through their impact on how the school is organised, the climate in the school and, especially, teachers and teaching. They can set the tone for teachers by encouraging new teaching practices and improvement of teachers' skills and by ensuring that teachers feel responsible for students’ learning. These practices are part of what is known as instructional leadership. In this indicator principals are compared by average age and work experience, measured in years and broken down by gender.