is it true that formatting my USB data travller extensivelly will reduce its storage capacity i heard that with every format its storage capacity reduced by some kbs is it true?
I hadn't heard that. However, such devices do have a limited life and are rated for a certain number of fill/erase or format cycles, beyond which they may become unwriteable or unusable. Typically as portions of the memory become unusable, they are marked as bad and are not used, which of course will reduce the total amount of available storage. But this will happen intermittently, not in a predictable or steady way. The number of operations required to make a drive unusable is typically very high, on the order of millions.