This site contains the APIs that you can use within Lenses.
Built-in are the built-in APIs that you can call within a script in Lensses.
Packages are additional APIs which are available when you've imported the package into your project, such as from the Asset Library.
TypeScript are additional APIs are available when you create your script in TypeScript.
Recent Changes to Documentation
You can now access the Full API List, which provides an alphabetical sorting of modules, namespaces, functions, methods, etc.
Some namespace+interface are now combined into an Abstract class with Protected constructor.
There is no change to how you can write your code, but it should make it easier to find an API in the doc as you don't have to find something in multiple places!
This more closely resembled how the documentation was laid out in Lens Studio 4 and below.
Tips and Tricks
On the top right corner, you can find a search icon to help you search the docs.
When namespaces include : in its name, you will likely need to import it first.