RNA splicing is a form of RNA processing for the maturation of mRNA. During splicing, introns in the precursor messenger RNA (pre-mRNA) are removed and exons are joined, leading to the formation of a mature messenger RNA (mRNA). Several methods of RNA splicing exist in nature, for example, self-splicing, tRNA splicing and splicing by spliceosome. The type of splicing depends on the organism, structure of intron, and the requirement of catalysts.