Carrots are a biennial plant, which means that it completes its life cycle in two years. During the first year, it stores food (the root) to prepare for what it will need to produce flowers and seeds in the second year. Keep a few carrots for the following year and you will see them flower.

The flowers form umbels, very similar to Queen Annes Lace. Seed collection will be easy.

Wow! I never knew that; how interesting!

I'm new here and glad I came!

~Amanda in Austin

Your carrots will also cross with Queen Anne's Lace. The recommended isolation distance is 1/2 mile.

A question about carrots. I have planted some seeds and they all seem to have come up. Now I have my garden ready and can transplant them. Will it be okay to try to transplant each and every one, or should I thin them out? Also, someone here mentioned to leave them for a year. Does that mean to just let them winter over? Maybe cover them up with leaves or mulch or something and they'll come back next year with flowers? Thanks. I'd appreciate any help as I am very inexperienced with this.
Katie

Just thin them out.
You only leave them for a year if you want to collect seeds from the flowers. Otherwise it's a waste of space that could be used for planting veggies next year.