Removal of introns and joining the exons in a defined order in a transcription unit is called

In some eukaryotes, genes consist of coding nucleotids sequences, which are separated from each other by blocks of non-coding sequences. The coding sequences here are called exons and non-coding sequences are called introns. The primary transcript from a typical eukaryotic gene contains introns as well as exons. The introns are removed from this primary transcript by a process called RNA splicing.