Alternative splicing

[Justanotherhuman]

From my understanding, some sections of pre-mRNA can code for both exons and introns. After splicing, mature-mRNA has regions which can act as both introns and exons. This means that the same gene can code for different protein.
I feel that my understanding is lacking, could you clear it up for me please? Also if you could link it to increase in genetic diversity it would be amazing
Thankyou

[alanihale]

After splicing, mature-mRNA has regions which can act as both introns and exons. This means that the same gene can code for different protein.

Post-transcription/mature mRNA won't have introns as the introns were removed as a part of the post-transcription modification. This leaves just the exons.
Alternative splicing is when the exons are reshuffled.
(i.e. if it was originally Exon 1 - Exon 2- Exon 3 in a chain alternative splicing might produce Exon 2- Exon 1 - Exon 3)
This is a suggested reason as to why the body's proteins are so diverse despite the limited amount of DNA present.
Hope this helps!