What is the use of two buttons behind the Samsung galaxy tab a

[AC Question]

What is the use of two buttons behind the Samsung galaxy tab a?and why it get extremely heated?

 

[Sam_Gs7]

Review these answers on this AC-Thread: It doesn't refers specific to the
Samsung: Tab-A: But explain the usage of those rear Phone buttons
Link: http://forums.androidcentral.com/samsung-galaxy-tab-s10-5/473771-physical-button-tablet.html