Dominant & Recessive

Looking through this site, you will hear about dominant and recessive traits. What do these mean?

When speaking of genetics, different letters are used to represent the different locii. For instance, 'd' stands for the locus that is normally called 'dilution', 'M' means 'Merle' etc. A dog (or any other animal) has two letters per locus - one inherited from the mother, and one from the father. What you inherit and from which parent is random.
Traits can be Dominant or recessive. When a trait is Dominant, it means just one 'letter' is needed for it to show in the animal, while a recessive trait must use both up both 'slots' or it won't show. For instance, the most common type of black coat in dogs is a dominant trait, while a red coat is recessive. Capital letters are used for dominant traits, lower case for recessive. In this case, "E" stands for 'Black' and 'e' means 'red'. So, if a dog has EE or Ee on that locus, the E will override the e, and the dog will be black in colour. It's only if the pup has ee that its coat will be red.
A dog that has two different letters on a locus (eg. Ee) is called heterozygous for that trait. If the two letters are the same (eg. EE or ee), it is called homozygous.

Black/tan German shepherd/Shetland sheepdog