anarchism is anti-authoritarianism.
Anarchists believe in the inherent dignity and worth of the human individual. Anarchists are anti-authoritarians because they believe that no human being should dominate another. Domination is inherently degrading and demeaning, since it submerges the will and judgement of the dominated to the will and judgement of the dominators, thus destroying the dignity and self-respect that comes only from personal autonomy. Moreover, domination makes possible and generally leads to exploitation, which is the root of inequality, poverty, and social breakdown.
In other words, then, the essence of anarchism (to express it positively) is free co-operation between equals to maximise their liberty and individuality.
Co-operation between equals is the key to anti-authoritarianism. By co-operation we can develop and protect our own intrinsic value as unique individuals as well as enriching our lives and liberty.
No individual can recognise his own humanity, and consequently realise it in his lifetime, if not by recognising it in others and co-operating in its realisation for others.
While being anti-authoritarians, anarchists recognise that human beings have a social nature and that they mutually influence each other. We cannot escape the "authority" of this mutual influence, because the abolition of this mutual influence would be death. And when we advocate the freedom of the masses, we are by no means suggesting the abolition of any of the natural influences that individuals or groups of individuals exert on them. What we want is the abolition of influences which are artificial, privileged, legal, official. In other words, those influences which stem from hierarchical authority.