A common term to describe maxing a skill of one of your horses. It is named due to the text of the skill changing to bold once achieved. It plays a role in what inborn skills a foal gets from its parents, as well as the BLUP. Bolding is used to increase the BLUP of your horse. The top 3 skills of your horses breed must be maxed out. To see what the skills are, check the Genetics tab below your horse. The top skills have the highest numbers, and is the same for mixed-breed horses. Each player has his/her own way of training their horses. These tips are from the Howrse UK forums [1]