In the Middle Ages, a squire was the shield- or armour-bearer of a knight. Boys served a knight as an attendant, doing simple but important tasks, such as saddling a horse and caring for the knight's
Wolfram von Eschenbach and his squire (Codex Manesse, 14th century)
The Squire - Ellesmere Chaucer
A page or page boy is traditionally a young male attendant or servant, but may also have been a messenger in the service of a nobleman.
Squire
…Eventually, a lord of the manor might come to be known as a "squire". A squire was typically a young boy, training to become a knight. A boy became a page at the age of 7, then a squire at age 14. Squires were the second step to becoming a knight, after having served as a page. A squire was responsible…
Lord Patten, robed as Chancellor of Oxford University, assisted by a page
Alof de Wignacourt and his page, by Caravaggio, c. 1608
The Queen and the Page, by Marianne Stokes, 1896
Painting of a page boy with slave collar, Dutch, 17th century