The crimson color stands for Castile as Madrid has been historically Castillian, and the stars represents each of the administrative areas of the province of Madrid, which are the City of Madrid, Alcalá de Henares, Torrelaguna, San Martín de Valdeiglesias, El Escorial, Getafe and Chinchón.
The crimson color signifies Castile because Madrid has historically been part of Castilian territory, while the stars represent each of the administrative regions within the province of Madrid: the City of Madrid, Alcalá de Henares, Torrelaguna, San Martín de Valdeiglesias, El Escorial, Getafe, and Chinchón.