If there is an item (web-link or document or image) that you use very frequently or find very useful, should you 'star' it (as in Gmail) or 'favorite' it? Are 'marking as starred', 'liking' and 'adding to favorites' similar?
'star' 'exclamation mark' 'light bulb' 'tag' icons could work - depends on what you want
Liking, Starring, and Adding to favorites are really different
- Like - is mainly sharing, and saying thanks
- Starring - is marking something for yourself for future findability
- Adding to favorites - means that you like something and you want to return there regularly
I would also add 'tag'-ing (like in delicious)
- I usually 'tag' bunch of things with my account, because I found tham really useful in a given topic, and maybe it will be very useful again (or I can send it to somebody else if asked)
- "Star" I've seen in multiple places, it's ok even though the verbing weirds me out.
- "Like!" is a good choice for a social app, free of grammatic pains.
- with "favorite" I'd stick with "Add to favorites".
Alternatively, When you have a volatile list, and want to make favorites sticky, a pin is a common methaphor: