Skin tags are just tiny pieces of "loose" skin. A lot of times they will form under your armpits. They are not dangerous, but can be annoying and unsightly. You can have them removed by a dermatologist, or any other doctor that can safely snip them off.
Skin tags, which are also known as acrochordon, are small tumors that are benign in nature. They skin tags are not dangerous and they mostly appear in the armpit, neck or groin region. Read more, en.wikipedia.org/wiki/Acrochordon.