In short: both, depending on what you mean. Buddhism has ethics, ritual, monastic communities and a spiritual goal, which are marks of a religion. But it does not centre on a creator god and invites people to test its teachings, so many call it a philosophy or a path of training. Most practitioners simply say it is a way of life.
In the Buddha’s words
Please, Kālāmas, don’t go by oral transmission, don’t go by lineage, don’t go by testament, don’t go by canonical authority, don’t rely on logic, don’t rely on inference, don’t go by reasoned train of thought, don’t go by the acceptance of a view after deliberation, don’t go by the appearance of competence, and don’t think ‘The ascetic is our respected teacher.’
AN 3.65, translated by Bhikkhu Sujato (CC0)
Why people say "religion"
- Temples, monks and nuns, ceremonies and festivals.
- Ethical precepts and a view of life and death. See the five precepts.
- A spiritual goal: the end of suffering. See nirvana.
Why people say "philosophy"
- No creator god; the Buddha is a teacher.
- Emphasis on direct experience. See the Kalama Sutta.
- Practice of mind training, which many do without becoming Buddhist.
Basics: what is Buddhism? · what Buddhists believe · how to become a Buddhist
Questions people ask
Is Buddhism a religion?
By most definitions yes: it has teachings, ethics, ritual, monastic communities and a spiritual goal. But it does not centre on a creator god, so many describe it as a philosophy or a path of training.
Do Buddhists worship the Buddha?
Buddhists show respect and gratitude to the Buddha, with bowing and offerings, but he is not worshipped as a creator god. He is honoured as a teacher who showed the way.
Can I practise Buddhism and keep my own religion?
Many people meditate and follow Buddhist ethics alongside another faith. Whether you formally take refuge is up to you and your teacher.