Once you’ve identified the problem you’re solving and understand what kind of pain this problem causes you can start to address the extent of the problem as well as who is experiencing it. We want to gauge our Total Addressable Market or TAM in a few ways. First we want to identify what kind of revenue you can achieve by solving the problem for 100% of the people currently experiencing this problem. Next we’ll expand this TAM by defining the larger opportunity around it. Who can possibly use our services over all? It’s important to start quantifying these populations as they inform how many potential customers you can acquire over the life of the business.