It's about the annotation triggering a code pre-processor.

For example in Lombok, the @Data annotation will create a getter and a setter for every private member, and @Getter and @Setter will do the individual methods respectively.

Annotating a class will do every private member, or you can annotate a specific member.

A lens is a shortcut to making a getter/setter for something several elements deep, where instead of calling:

`parentObject.getChild().setChildAttribute()` you can call: `parentObject.setChildAttributeViaLens()`

and not need to write multiple functions in both classes, or even use multiple annotations.