Biometrics, what and how

Humans have used body characteristics such as face, voice, gait, etc. from the day that mankind existed to recognize each other. Some characteristics don’t change over time and some do. And since each on has a unique characteristics that no other share we humans have thought of using that in our daily life, The main aim of using it after 9/11 is for security reasons. So what characteristics do we use? Are they accurate? Can we depend on them in our daily life routine? I have tried to cover all of the characteristics that are used in Biometrics, How they are used, and what are the disadvantages of using them.