THANK YOU SO MUCH!!! This makes way better sense now.
Though let's say that the SNP occurs in the introns (non-coding) regions of the DNA sequence, which happens more frequently (apparently), how would it be of any use given there's no phenotypic change observable?
No worries, happy to help
SNP occurs more frequently in the introns in specific organisms (though most) as the only reason for that is because most eukaryotes have a significant higher percentage of introns compared to exons (while prokaryotes have the opposite ratio). Though the phenotypic change is not observable, the alteration of sequence of nucleotides can be identified through DNA analysis/testing, usually using blood sample, or any somatic tissues such as hair.
Also, keep in mind that mutations in introns can have an effect of some magnitude. As introns (promoter, silencer & enhancer) are responsible for regulation of gene expression, positions of introns can also rate of transcription & hence the expression of an gene. As well as that a SNP in the exons can also produce no effect as mentioned earlier, some sets of codons code for the same amino acid so the conformation of the final protein remains the same though the DNA sequences have changed.
Even though some SNPs don't result in any phenotypic change, they can be
indicators or a potential risk of diseases such as cancer or be a sign of familial lineage, because when the SNP is inherited the alleles near the SNP are also inherited, hence we
know that if a person has a specific SNP, they likely also have the surrounding alleles. That's why for a SNP to be a SNP is has to occur at a specific frequency, as then we can use them for identification to predict the other alleles that may have been inherited along side the SNP.