As @Rick_SAS says, by the time this feature was named "DS2" and released, it was offered as a more object-oriented, multithreaded version of the DATA step. It can be extended by the use of DS2 packages, which are reusable modules that encapsulate their own feature sets.
When the project began as TSPL (table server programming language), the focus was to bring the power of the traditional DATA step to a process that could be embedded within databases. It's what allows lots of SAS-based code (including model score code) to execute within databases (like Oracle or Teradata) without having to first move the data out into a SAS process. This data movement is often the most time-expensive part of data management, and model scoring needs to be fast especially in transactional systems. DS2 allows you to "bring SAS to the data" and save on all of that.
This embedded process and extension of SQL passthrough is part of the SAS/ACCESS offerings (and there is a SAS product for each database vendor supported), but DS2 itself has always been part of Base.
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