Usability, ergonomics what the different?

The essence of usability is about task completion – getting thing done. Usability is about making the task fit the human, not vice versa. Whether you are checking your email, adding people on social networking site, ordering from an online store or posting photo involves task.

International Standards Organisation (ISO) DEFINE usability as

The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.

Keyword here is “to achieve specified goals” While ergonomics () is about making the thing fit the human, not vice versa