In-breeding: This is the breeding of closely related animals. Brother-Sister, Parent-Offspring, ½ brother- ½ sister.
Line-breeding: This is the breeding of animals that share common ancestors but are not closely related. For example, the dogs may share a common great-grandparent. Line breeding is another way to help "set" or "fix" desirable traits. With line breeding, you breed animals that are related, but you are also routinely introducing genes from other lines into the genetic mix. It takes longer to fix the desirable traits this way, but doing so lowers the risk of those problems associated with repeated in-breeding.
Out-cross: This is generally considered the breeding of animals with no common ancestors within the first 4 or 5 generations. Out-crossing will tend to produce fewer offspring affected by hereditary disorders, especially if there is extensive family information available and shared. Out-crossing is not for those who want to get breeding program results fast... but when done carefully, with in-depth patience, it does offer the potential for producing generations of healthy pups and improving the overall gene-pool of the breed. Out-crossing does not guarantee that the animals will not develop genetic disorders, but it does tend to reduce the numbers of affected offspring.
Out-Breeding: This is the breeding of two dogs who not only are the product of two distinctively different lines, but on top are not the product of line-breeding. Out-Breeding is seldom employed since in most breeding programs dogs that would qualify for out breeding don’t exist anymore. The mating or breeding of distantly related or unrelated individuals. Outbreeding often produces offspring of superior quality because it increases homozygosity, thereby sharply reducing the risk of deleterious recessive genes being expressed. Crossbreeding is the most common form of outbreeding.