Most files are not just a jumbled mess of bytes. There is an order and pattern to the bytes within the file.
This pattern is called the file 'structure'.
When a software application creates a file, it will do so in a certain way so that the file can be read back. For example a file structure might be something like this:
<Header data> 24 bytes
<Name field> 36 Bytes
<photograph> up to 1MB marked by <End of picture>
So if a software application needs to read back the file it now knows that the first 24 bytes is to be the header (whatever that means to the software) followed by 36 bytes representing a name. Then up to a megabyte that is marked by the "end of picture" set of bytes. And so on.
This is why it is very useful for software programmers to have a published file structure. For example, Adobe have released the file structure of their Flash SWF file. This means that other companies can now read and create SWF files as well.
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: File Structure