We describe our job by saying I am or I'm and then naming the position. Notice that Sam says he is the C.E.O. or Chief Executive Officer of his company. When someone asks who you work for, it can be useful to also tell them what your job is. When meeting someone, it helps them if you offer information before they ask. This makes the conversation more relaxed. Now Sam is going to ask you who you work for and what your position is - answer his questions with your own answers: