What causes nose bleeds?

The most common cause of nosebleeds is dry air. Dry air can be caused by hot, low-humidity climates or heated indoor air. Both environments cause the nasal membrane (the delicate tissue inside your nose) to dry out and become crusty or cracked and more likely to bleed when rubbed or picked or when blowing your nose. Also colds, blowing with force, drugs. Most are not serious. (I’ve personally never had a nose bleed)

Not true , they can fall or something