Rosemary is a perennial, woody herb that has fragrant evergreen leaves. It is native to the Mediterranean region and is part of the same plant family that mint comes from. The name that it has been given comes from the Latin word rosmarinus - which means ‘dew of the sea’.
An annual plant is one that completes its whole life cycle in one complete year. In short this means that its growth cycle consists of going from seed to seed before it dies off all in one growing season.
Annual plants have this type of growing season in order to produce and propagate. You will find that removing the flowers before the seeds have fully matured will help to create more flowers and more seeds.