Significance of " /proc/<pid>/root"

[Arun M Kumar]

What is the significance of the directory named root inside /proc/<pid> ?

ex:
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arunkumar at arun-ThinkPad-Edge-E530:/proc/2543/root$ ls

bin   cdrom  etc   initrd.img      lib         media  opt   root 
sbin     srv  tmp  var      vmlinuz.old
boot  dev    home  initrd.img.old  lost+found  mnt    proc  run selinux  
sys  usr  vmlinuz
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