Stwintrons (spliceosomal twin introns) are complex intron structures that participate in the regulation of cells and enable alternative splicing, thus promoting multiple gene expression. Similar to the structure found in the chloroplast of algae, these structures need two successive splicing operations to be completely removed from the mRNA. They have a unique structure where an "internal intron" must be removed in order for the "external intron" to be spliced properly. They were first investigated by the Department of Biochemical Engineering at the University of Debrecen in 2013. The aim of this thesis work is to summarize recent scientific insights made on the literature about stwintrons.