The word POB is widely used in the kpop community. For new people it can be confusing about what the word exactly means and the answer I got from a google search made me even more confused so I will try to explain it very simply for you.
POB is an abbreviation of Pre-Order Benefit and POB is usually physical things such as a photocard, poster, postcard etc. you get when pre-ordering an album. POB are exclusive and different from the normal inclusions that come with the album.
The term POB is most used for Pre-order benefit photocards. POB photocards tend to be highly desirable among kpop fans and collectors. They are different from the in-album photocards and tend to be different from store to store. Stores that hold pre-order events with POB get exclusive photos from the artist’s company that they can use on the photocards.
Stores hold events like pre-order events which contain POBs and they also hold events for fansigns where they give out fansign photocards/store exclusive photocards. I have a photocard guide if you want to learn more about the different types of photocards.
How can I get POBs?
You have to buy albums to get the POB and most stores do 1 or 2 POB for each album purchased so you must buy multiple copies of the album to get a full set of POB or you can buy them on marketplaces. POB tend to be more expensive than album photocards.