* The Church: For much of history, particularly in Europe, the Church (Catholic Church primarily) was a major provider of education, particularly at lower and higher levels. Monasteries and cathedrals often ran schools.
* The State/Government: Increasingly, especially in the modern era, governments at various levels (local, regional, national) have taken on the primary role in providing and regulating education. Public schools are a prime example.
* Private Institutions: Throughout history, private schools, academies, and tutors have also played a significant role in education, particularly for the wealthy or those seeking specialized instruction.
* Families: In many cultures and throughout history, families themselves have been the primary educators, particularly for basic skills and cultural transmission.
Therefore, the answer depends heavily on context. You need to specify a time period and geographical location to get a more precise answer.