Thyroid Nodules, growths that can be found in the thyroid gland.
Nodules are not exactly uncommon. Though most are not cancerous, but 'side affects' (for lack of a better term) of the damage resulting from thyroid autoantibodies, such as those involved in Hashimoto's Thyroiditis (Hashi's)
Though it is definately wise to have nodules checked, finding one should not automatically be considered to be indicative of thyroid cancer.
The most common test, so far, is an FNA (Fine Needle Aspiration). A needle is used to penetrate the nodule and some of the material is removed and then tested/identified to find out if it is cancerous or not.
Some fine the procedure very uncomfortable, others do not. Since I've not had need for the proceedure, I really can't comment much on it.. My suggestion would be to find someone in a support group that has had it and ask them what it was like for them.
The more you know about tests and proceedures like this before you go in, the easier and less scarry it is... at least that is the way that it is for me.