Alternative splicing is a process that occurs in eukaryotes. In this, a given transcript of pre-mRNA which has been transcribed from one gene can be chopped and reconnected in different ways to yield various new mRNAs which then exit the nucleus to be translated in the cytoplasm.

Several proteins can be encoded in a DNA sequence whose length would only be enough for two proteins in the prokaryote way of coding.

A common myth is that alternative splicing is responsible for humans supposedly being the most complex animals, saying that humans perform more alternative splicing than the other animals. However, this is not the case. A study conducted on the subject found that "the amount of alternative splicing is comparable, with no large differences between humans and other animals. The "record-holder" for alternative splicing is actually a Drosophila gene with 38 000 splice variants called Dscam.