Illana is a town and municipality in the province of Guadalajara, in the autonomous community of Castile–La Mancha, Spain. It lies within the natural region of La Alcarria, a rural area of central Spain known for its rolling terrain, cereal fields, and honey production.
As a municipality, Illana covers the town itself together with the surrounding countryside, and its local administration is based in the town. Like other settlements in the province of Guadalajara, it forms part of one of the most sparsely populated parts of Spain, where small towns serve as the main centres of population across a wide rural landscape.
The town's location in La Alcarria places it within the broader Castilian countryside of Guadalajara province, northeast of Madrid. Its identity is tied to this agricultural setting and to the administrative structure of Castile–La Mancha, the autonomous community to which both the province and the municipality belong.