As we can see, there are almost endless use cases that you can imagine. This really gives Lambda some extra flexibility and will help developers deliver code faster. At a high level, these use cases fall into three categories:

• Custom modules, libraries, or functions that can be used by multiple functions
• Third-party dependencies 
• Static data that can be shared with multiple functions

A connection you have probably made already is how ideal Lambda layers are for distributing custom runtimes. If you are going to the effort of bringing your own runtime to Lambda, then you're likely going to run more than one function using that custom runtime. Lambda layers are the perfect way to share the custom runtimes across functions.

I encourage you to use layers in your own Lambda development for any of the use cases in this section. In the next section, we're going to explore the aspects and considerations we need to make when using Lambda in production.