Explain process of reasoning. What are the general mistakes seen while reasoning?

Reasoning helps us to make good arguments.
People often make a generalization based on a sample that is too small or is biased in some way. 
It’s called “ hasty generalization.”

A hasty generalization is one of the many kinds of mistakes in reasoning. We all sometimes believe things for bad reasons. That is, we think that one statement can make another statement seem true, when it doesn't. We allow our wishes and interests to influence our reasoning. This way we are being biased and the reasoning that supports our argument is not strong enough. When we learn to recognize the mistakes we all make, we can avoid them. There are words for the most common mistakes we make in reasoning, and learning the words makes it much easier to spot the mistakes. Effective thinking can be done only by avoiding such mistakes.