Thai Basil is one of the most widely used herbs in Southeast Asia.  You will find this in many of the Thai and Vietnamese dishes.  The flavor is as slightly spicy with hints of licorice and very aromatic.  Under the right condition, this herb can grow as large as pepper plants.  Once they begin to flower, the flavor and texture will change, so pruning is recommended.  Pinch off all buds as soon as you see them to keep the plant growing vigorously while maintaining tender leaves with better flavor.