Quote from: shakil77 on May 12, 2018, 04:18:23 PM

which purpose we are uses private key ?

You already know what it is for, why are you asking this question?
You showed that you understand the use of private keys in the quoted posts below

Quote from: shakil77 on May 11, 2018, 09:06:59 AM

you have a privet key and no body know about your key that key secure your bitcoin from the thief or others. or you can use software,a hardware wallet can also secure your bitcoin.

Quote from: shakil77 on May 11, 2018, 05:43:57 PM

try to save your private key . there are many phishing site where hacker send many links if you click on that you lost your every thing. especially in your gamil account so don't click any link that is not familiar to you.do not share your password with yours friends,your relatives and try to avoid sign in your gmail account with other person device.