>This is the first time I am using .dbc ,
>so I have some doubts
>
>Is it necessary to backup .dbc everytime I do a backup ?
>
>Or can I backup only dbf , cdx, fpt, and sometimes dbc ?
>
>My doubt is if dbc changes its structure or not, as customer add data to his tables
>
>( am I afraid my software will not be able to zip .dbc all the time)

If you want to backup a DBC, you need to include its corresponding index and memo files (DCT, DCX). When backing up data, it's my practice to always include all of these file extensions:

DBC
DCT
DCX
DBF
CDX
FPT

If the user ever has to restore an entire backup into a new directory, then you must have the database container files as well or else your application will crash.