Rosemary, the plant

Rosemary by nature is a drought tolerant plant and develops a massive root system. It grows in search of water, so if you have a pot indoors, you need to water it each day. It does better outdoors, in general. Keeping it in a big enough pot, if you do have it indoors is a must.
Outdoors, it needs to be in well drained soil. It likes a sandy soil, and give plenty of water in the beginning. After new growth appears, you can back off on some of the watering.
Rosemary is winter hardy down to 20 degrees. It requires bright light, and actually likes poor soil conditions, with good drainage. You can feed it occasionally a plant food, and keep it consistently watered. The foliage doesn't like to be wet, best to water from base.
At a mature height, it will be 2-6 feet tall. The leaves have kind of a two tone coloring, darker green above, grayish white underneath. There will be small clusters of lavender/blue small flowers in winter and spring. The flowers attract birds, and bees.