Ok! Here are some facts about CoDominance.
It can cause cats to have spots or stripes!
It's responsible for the genetic variations in your phenotype.
In a punnett square, a homozygous dominant allele would look something like WWXX
In flowers, like the 4 o'clock plants, it has a chance to breed mixed colors.
When Calico cats and Tabby cats breed, the little ones have a higher chance of being a Tabby cat. They also have a chance of being white, black, or also being a calico.
In blood, A B and O are the different types you can have. A and B are both dominant to O. So blood type AB is a codominant trait.
This picture shows the possibility of combinations of blood types.
People also can pass genetic disorders, for example;
if both member in a couple have a dominant gene for genetic disorders such as 'breast cancer, down syndrome,' or any other kind of genetic disorder, their disorder has a chance to change and co develop with a new gene.
So in short; Co-dominance is when two alleles are neither dominant or recessive to each other where they both create a gene that combines them both.
To end this, I'll show a funny picture that Josh showed me. (I thought it was pretty awesome, but I don't think that's how co dominance works.