Transformations are functions applied on RDD, resulting into another RDD. It does not execute until an action occurs. map() and filter() are examples of transformations, where the former applies the function passed to it on each element of RDD and results into another RDD. The filter() creates a new RDD by selecting elements from current RDD that pass function argument.
val rawData=sc.textFile("path to/movies.txt")
val moviesData=rawData.map(x=>x.split(" "))
As we can see here, rawData RDD is transformed into moviesData RDD. Transformations are lazily evaluated.
