1. used to refer to people or things previously mentioned or easily identified
Usage: plural of ‘one’
2. used to refer to particular people or things from a group
Usage: often used with adjectives or descriptive phrases

Examples

• I like the red apples better than the green ones.
• These books are more interesting than the ones we read last year.
• The tall ones in the back should move forward.
• Which cookies do you want? The chocolate ones or the vanilla ones?
• The new students seem friendlier than the old ones.
• I need batteries, but not the expensive ones.