# Basics to Remember

Before diving too far into code, it's important to remember the role SQL now plays in many ETL pipelines.

In the olden days, a pipeline was by default made nearly entirely of pure SQL building sets from one carefully-maintained local server to another, all under the watchful gaze of a local sysadmin. Since the rise of SaaS, particularly for financial and sales operations, ETL functions often start with an external product, and usually pipe through or to other off-site products.

This is reflected heavily in some best practices (particularly those developed by the SaaS themselves), but not in other works. Flipping between the two can cause a bit of whiplash. Keeping the context of the documentation in mind while reading is an important step.
