grammar.verbs.gerund-uses
What the gerund can and cannot do
The gerund expresses progress (está comiendo), manner (aprendí practicando), and simultaneity — but never works as an adjective or after prepositions.
grammarB1, B2✓ Revisadov0.1.0
Explicación
Legitimate jobs: progressive with estar/seguir/ir/llevar, manner and means (se fue corriendo, lo resolví hablando), and backgrounded simultaneous action (caminando por el centro, vi a Marta).
Off-limits (unlike English -ing): after prepositions (antes de salir, not *saliendo), as a noun (nadar es sano), and as a noun-modifying adjective — 'a flying object' is un objeto volador or que vuela, not *volando.
A good test: if you can replace the English -ing with 'while/by …', the Spanish gerund fits; if it names a thing or modifies a noun, it does not. So 'I like swimming' is me gusta nadar (infinitive) and 'running water' is agua corriente (adjective), but 'I learned by listening' is aprendí escuchando.
Ejemplos
He left running / he ran off.
Región: global
The singing man is my neighbor.
Región: global
I learned by listening, not by reading manuals.
Región: global