Most people are a combination of different somatotypes.
Ectomorph = tall, skinny (it's pretty obvious to tell if you are an ecto). Fast metabolism, making gains in weight hard.
Endomorph = pear shaped. Narrower shoulders, thick knee/ankle joints and heavy set legs. Slower metabolism, making them prone to fat gains.
Mesomorph = naturally muscular. A pure mesomorph will have good natural muscle size, a relatively fast metabolism yet they can gain/lose weight easier than others and relatively small joints.
Like i said though, you will most likely be a combo of different somatotypes.
I am a mix of meso/endo. The meso somatotype is more dominant though in me.