A nun's veil and wimple are symbolic garments that publicly indicate her acceptance in a religious order. Together with her habit, they outwardly distinguish her from secular society.
The ceremony in which a nun avows herself to her order is called taking the veil, explains an essay published in the "Proceedings for the Western Society for French History." For a nun, taking the veil is an important sign of humility and service to her belief in God.
Becoming a nun is a serious undertaking in which a woman receives a "call" to serve, or become the bride of Christ. As detailed in the article "How Nuns Work," the process can take up to a decade with physical and mental examinations, spiritual examinations, as well as paperwork and the relinquishment of any earned salary. The candidate must then live fully as a nun for several years before taking her final vows.
The attire of the nun dates back to the Middle Ages. "Global Sisters Report" indicates that some orders have chosen to eschew the traditional habit in favor of more modern clothing; however, others remain faithful to a tunic and veil. For example, a recent NPR article follows young nuns of the Dominican order who favor the simplicity of their long white habits and black veils.