SQL JOINs: how two tables become one answer (INNER, LEFT, RIGHT, FULL)

customers (tap a row to remove it)
id	name

orders (tap a row to remove it)
id	customer_id	item

result
name	item

Orange rows in the source tables found no partner. Tap any row to take it out, or tap it again to bring it back, and watch the result change. NULL means "nothing here".