hold on to
phrasal verbhold on (to something/somebody) | hold on to something/somebody 
- [no passive] to keep holding something/somebody
- Hold on and don't let go until I say so.
 - He held on to the back of the chair to stop himself from falling.
 - It’s very windy—you’d better hold on to your hat.
 
 
hold on to something | hold onto something 
- to keep something that is an advantage for you; to not give or sell something to somebody else
- You should hold on to your oil shares.
 - She took an early lead in the race and held on to it for nine laps.
 
 - to keep something for somebody else or for longer than usual
- I'll hold on to your mail for you until you get back.