The dynasty had a crucial role in the formation of the French state. Initially obeyed only in their own demesne, the Île-de-France, the Capetian kings slowly but steadily increased their power and influence until it grew to cover the entirety of their realm. For a detailed narration on the growth of French royal power, see Crown lands of France.
Members of the dynasty were traditionally Catholic. The early Capetians had an alliance with the Church. The French were also the most active participants in the Crusades, culminating in a series of five Crusader Kings – Louis VII, Philip Augustus, Louis VIII, Saint Louis, and Philip III. The Capetian alliance with the papacy suffered a severe blow after the disaster of the Aragonese Crusade. Philip III's son and successor, Philip IV, humiliated a pope and brought the papacy under French control. The later Valois, starting with Francis I, ignored religious differences and allied with the Ottoman Sultan to counter the growing power of the Holy Roman Empire. Henry IV was a Protestant at the time of his accession, but realized the necessity of conversion after four years of religious warfare.
The Capetians generally enjoyed a harmonious family relationship. By tradition, younger sons and brothers of the King of France are given appanages for them to maintain their rank and to dissuade them from claiming the French crown itself. When Capetian cadets did aspire for kingship, their ambitions were directed not at the French throne, but at foreign thrones. Through this, the Capetians spread widely over Europe.
In modern times, both King Felipe VI of Spain and Grand Duke Henri of Luxembourg are members of this family, both through the Bourbon branch of the dynasty. Along with the House of Habsburg, it was one of the two most powerful continental European royal families, dominating European politics for nearly five centuries.
The name of the dynasty derives from its founder, Hugh, who was known as "Hugh Capet". The meaning of "Capet" (a nickname rather than a surname of the modern sort) is unknown. While folk etymology identifies it with "cape", other suggestions suggest it to be connected to the Latin word caput ("head"), and thus explain it as meaning "chief" or "head".