From latin obligatĭo, the obligation is what a person is forced (forced) to make. It can be a legal tax or legal requirement. For example: "Paying taxes is an obligation for all citizens", "If you want to continue to work for us, you have an obligation to be on time every morning", "help the most disadvantaged is a duty of all those who were lucky to have a job."
An obligation may therefore be a link that leads us to do or refrain from doing something, fixed by the Act or standards. In several countries, vote in elections is a duty of all citizens who meet certain conditions (be, have an identity card, etc.). If the person meets the conditions to be able to vote and she decides not to go to vote, there will be wrong not to perform his civic duty.
The obligation may also be linked to a religious precept. In this case, it is not the Act which imposes the penalty in the event of non-compliance, but God or even a religious institution. The Jews are required not to eat the meat of swine, while Christians have an obligation not to have sex before marriage.
It is possible that the obligation arises from the consciousness of itself or its morals. If a man learns that a friend is in trouble, he may feel obliged to help him and to stop what he is doing to help him.