[U-Boot] Purpose of Data partition in Partition Layout

[Rajdeep Vaghasia]

Hi all,

My current default partition layout is as follow:
1) u-boot,
2) environment variables
3) kernel,
4) filesystem

I have seen in some implementations, that there is one partition of "data"
after the filesystem's partition as follow:
1) u-boot,
2) environment variables
3) kernel,
4) filesystem
5) data(or rest)

What is the purpose of this data partition?

Who reads/writes there (kernel or filesystem(like jffs2)) and *How*?
        If kernel writes there, then do we have to change kernel
configuration? If yes, then what changes are required?

What happens in case, when I don't keep that separate partition of data and
only filesystem is given the rest of the flash memory(as I have used)? And
How it differs from the partition layout with data as the last partition?

I don't know about this.

Please, help me understand these.