Education takes place both formally through institutions like schools as well as informally through family discussions and lectures. Formal schooling is directed by trained teachers. The availability and accessibility of schooling varies between high, middle, and low income countries and is often shaped by cultural and social factors. For example, in many places schooling is more readily available to boys than girls. While schooling aims to promote concepts like equal opportunity, in reality access differs based on factors like income level, gender and race. Sociologists view key functions of education as socializing youth, promoting cultural innovation, integrating society, and enabling social mobility, though some argue it also serves to maintain social inequalities.