salam. in our country, there's a yearly book fair that is arranged and everyone enjoys it in a festive mood. many food shops also sell foods in the fair. it happens in the same month every year. its a local custom. is it bidah?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.{C}

This is not a Bid'ah (religious innovation) and it does not fall under the definition of the scholars to this word (Bid'ah).

People do not do this as a way of getting closer to Allah [i.e. as an act of worship and obedience].

In addition to this, organizing such fairs, exhibitions and forums is good as it encourages people to read and learn.

Allah knows best.