The meaning of the term “squire” has shifted greatly over the centuries. When people use this term in reference to historical squires, they are usually talking about the apprentices who served knights on the way to their own knighthoods. In the modern sense, a squire is a member of the landowning gentry in England; the term is also sometime used in familiar slang, generally in an ironic sense.
Historical squires were young men, usually around the age of 12 or 13, who were interested in becoming knights. Initially such men worked as pages, glorified messenger boys who would carry messages, serve at the table, and perform an assortment of other menial tasks. While working as a page, a prospective knight would also begin training in the use of weapons, often absorbing this knowledge while watching the practice of older pages, squires, and knights.
Once a page had reached an appropriate age or level of training, he would be promoted to a squire. Squires acted as personal attendants for knights; they were also known as men-at-arms. A squire was responsible for keeping a knight's armor, weapons, and other supplies in good order. Squires also accompanied their knights on journeys to ensure that their needs were met, and in return for their service, they were offered advice and training. Squires also had the symbolic duty of carrying the knight's shield.
Once a squire was trained enough, he would have an opportunity to qualify as a knight. If he was deemed suitable for knighthood, he would begin a career, and sometimes be assigned a squire of his own. As a general rule, squires were members of the nobility, and part of a long tradition of learning through service, with an emphasis on using actual experience, rather than classroom learning, to educate young men and women who wished to pursue careers.
In the Middle Ages, the concept of knighthood began to shift. Formerly, knights were simply well-trained warriors who fought for specific lords. In the Middle Ages, however, knighthood came to be a conferred rank granted by the king, as part of an overall shift meant to centralize power in the hands of the monarch, rather than allowing regional lords to maintain their own private armies. Because knighthood was no longer an automatic rank, the squire came to be recognized as a distinct social rank, and squires were entitled to privileges like their own coats of arms.