Why is RDD called fundamental data structure of Spark when Dataframes and Datasets don't use RDDs

[Monica Shiralkar]

RDD is called the fundamental data structure of Spark. I have read this on multiple sources including https://sparkbyexamples.com/spark-rdd-tutorial/. We have Dataframes and the Datasets too. Why is RDD called the fundamental datasets when Dataframes and Datasets do not use it. Thanks

[Monica Shiralkar]

Thats because at the end , everything is decomposed into RDD.