Unity operates a store called the Unity Asset Store. There are a great number of assets available to Unity developers. The store is accessible directly on the Web at http://assetstore.unity3d.com. You can also open a window within Unity to display the Asset Store. This is accomplished by navigating to Window | Asset Store.
Regardless of how you connect to the Unity Asset Store, you'll see a hierarchical category listing in the top-right corner of the store:
Clicking on the triangular icons to the left of each category reveals subcategories. Some categories have multiple subcategories, which helps you find what you are looking for quickly.
When you click on a category, its contents will be viewable. Clicking on a specific asset will display several characteristics of that asset. These characteristics include:
Title
Publisher
Rating
Price
Purchase button or, in the case of free assets, an "Open in Unity" button
Version of Unity required
Description
Package contents
File size
Version number...
