grammar.articles.omission
Where articles drop out
No article in many fixed frames: en casa, a clase, por teléfono, tener coche, headlines, and most country names.
grammarB1✓ Reviewedv0.1.0
Explanation
Spanish leaves the article out in many fixed frames. Common set expressions go bare: estar en casa, ir a clase, ir a misa, hablar por teléfono, viajar en tren/avión, estar de vacaciones. Adding an article there sounds wrong.
Tener + a category noun also drops it when speaking generally: tenemos reunión, no tengo idea, ¿tienes hora?, buscar trabajo. The article returns once the thing is specified: tengo una reunión importante.
Most country names take no article today (vivo en Bolivia, viajo a Francia, es de México). A handful traditionally allow one ((el) Perú, (la) Argentina, (los) Estados Unidos) but the bare forms are now common everywhere, except the firmly fixed Estados Unidos.
Examples
Today I'm working from home.
Region: global
I don't have a car; I go by bike.
Region: global
I'm at home; tomorrow I go back to class.