What does it mean to work with ETL/ELT in the industry? Practical examples?

I have been trying to learn more about the concept of ETL. However everywhere that I search about this topic, I am presented with very generic theoretical information about it.

Is this all there is to this topic? From what I understand, ETL is about extracting data from a source like a data warehouse, transform into something like a business need by conditional filtering, etc, and then have it loaded somewhere for a business to be readily available, and then …

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