Can you explain how to create an AWS Lambda layer and provide the steps you have followed in your experience?

To create a Lambda layer:

1. Create a directory structure that matches the runtime, e.g., for Python: python/lib/python3.9/site-packages.
2. Install your dependencies into that directory using pip: pip install -r requirements.txt -t python/lib/python3.9/site-packages.
3. Zip the top‑level folder (the folder containing the python directory): zip -r layer.zip python.
4. In the AWS console or via AWS CLI, create a new layer: aws lambda publish-layer-version --layer-name MyLayer --zip-file fileb://layer.zip --compatible-runtimes python3.9.
5. Note the returned LayerVersionArn.
6. Add the layer to your Lambda function: either in the console under the function’s Layers section or via CLI: aws lambda update-function-configuration --function-name MyFunc --layers arn:aws:lambda:region:acct-id:layer:MyLayer:1.
7. Deploy or update your function code. The layer’s contents are now available at /opt during execution.

Key decisions: choose the correct runtime, keep the layer size under 50 MB (compressed), and version layers to avoid breaking changes.