user76811: If for some reason I made a wrong transfer to an unknown blockchain account, how do I know who is that belongs to?
In the first place I think it is unlikely a "wrong transfer" because the Blockchain address is not something you can make typo error. I am very suspicious how people can transfer my btc out without my authorization.
Many thanks for answers.

user13866: 
I made a wrong transfer to an unknown blockchain account, how do I know who is that belongs to?

In general you cannot readily find out who owns an address.
If the owner of the address is especially careless, a great deal of detective work may allow their identity to be discovered eventually. This is not a trivial process.


I am very suspicious how people can transfer my btc out without my authorization.

They don't need your authorization, they only need to have once seen your private-keys. That gives them complete control for all time over any funds subsequently arriving at addresses associated with your private-keys.
As an example, many online-wallets (also called web-wallets or hosted-wallets) give control of your private keys to employees of the hosting service and to anyone who hacks that service. So any dishonest ex-employee might be able to empty your wallet. This sort of thing happens with depressing regularity.

76811: <p>If for some reason I made a wrong transfer to an unknown blockchain account, how do I know who is that belongs to?</p>

<p>In the first place I think it is unlikely a "wrong transfer" because the Blockchain address is not something you can make typo error. I am very suspicious how people can transfer my btc out without my authorization.</p>

<p>Many thanks for answers.</p>
 13866: <blockquote>
  <p><strong>I made a wrong transfer to an unknown blockchain account, how do I know who is that belongs to?</strong></p>
</blockquote>

<p>In general you cannot readily find out who owns an address.</p>

<p>If the owner of the address is especially careless, a great deal of detective work may allow their identity to be discovered eventually. This is not a trivial process.</p>

<hr>

<blockquote>
  <p><strong>I am very suspicious how people can transfer my btc out without my authorization.</strong></p>
</blockquote>

<p>They don't need your authorization, they only need to have once seen your private-keys. That gives them complete control for all time over any funds subsequently arriving at addresses associated with your private-keys.</p>

<p>As an example, many online-wallets (also called web-wallets or hosted-wallets) give control of your private keys to employees of the hosting service and to anyone who hacks that service. So any dishonest ex-employee might be able to empty your wallet. This sort of thing happens with depressing regularity.</p>
