Most people have no idea, but there is a lot of people with low self esteem and confidence problems, it can be a child, an adolescent or an adult. There are 3 basic reasons for low self esteem haredity, environment and education, those are the factors that influence our life values and beliefs.
Sometimes a child has low self esteem because his parents had the same problem or were very shy, however there are ways to help the kid improve his confidence and have a healthy life.
Education plays an important role because the child learns some of the most important things at school, they start to interact with friends and acquires his own personality. However, you must be careful, because if the child is upset by friends at school either physically or mentally then it will affect his self confidence. But also education is important because they acquire values and beliefs that will persist for life.
Another very important factor is the environment, which is a very dynamic factor, the environment involves the home, school, friends, family and any other place that he goes. He needs to see good relationships between his parents and be treat it with respect, otherwise if he sees constant losses or people make fun of him, his self esteem will be affected.
However, the reasons for low confidence can also be acquire as an adult, a traumas in your life, a social embarrassment, a bad body image, a bad relationship and many other things can be a cause for low self esteem.
You need to constantly reinforce your self esteem by doing new things and getting new skills. You need to set goals and be proactive, do not depend on anyone, you can do many more things than you can imagine. Be a positive person, your thoughts have a powerful influence in your self image, if you are constantly criticizing your self you will have problems of confidence.
As you can see those are the most important reasons for low self esteem, i encourage you to get the most out of your life and find help if you need it, read motivational books, biographies and anything that increase your self confidence.