user128115: Person A wants to send some bitcoins to Person B. How will Person A come to know about the Person B's address? And for every transaction Person B's address (as well as Person A's) changes. How will Person A keep track of these changes?

user13866: 
Person A wants to send some Bitcoins to person B. How will person A come to know about the person B's address?

Person B shows Person A a QR-code displayed on B's smartphone wallet. Person A uses their phone's wallet to capture an image of the QR-code and extract the address.
or
Person B spells out the address over the phone, and A enters into A's wallet as the receiving address.
or
Person B sends the address in a Facebook message
or
any of a thousand other ways people communicate information with one another.


And for every transaction Person B's address (as well as Person A's) changes. How will Person A keep track of these changes?

Person A and B do one of the above each time A needs to send B money.

user5406: Usually, when people want to pay each other, they are already communicating as they have been arranging some form of transaction. Just like with other settlement methods, the receiver communicates to the sender how they would like to receive payment.
The receiver may do so e.g. by sending an invoice, displaying payment instructions on the checkout page of their merchant website, copying their address into chat, or displaying a QR-code to be scanned with a handheld device.

128115: <p>Person A wants to send some bitcoins to Person B. How will Person A come to know about the Person B's address? And for every transaction Person B's address (as well as Person A's) changes. How will Person A keep track of these changes?</p>
 13866: <blockquote>
<p><strong>Person A wants to send some Bitcoins to person B. How will person A come to know about the person B's address?</strong></p>
</blockquote>
<p>Person B shows Person A a QR-code displayed on B's smartphone wallet. Person A uses their phone's wallet to capture an image of the QR-code and extract the address.</p>
<p>or</p>
<p>Person B spells out the address over the phone, and A enters into A's wallet as the receiving address.</p>
<p>or</p>
<p>Person B sends the address in a Facebook message</p>
<p>or</p>
<p>any of a thousand other ways people communicate information with one another.</p>
<hr />
<blockquote>
<p><strong>And for every transaction Person B's address (as well as Person A's) changes. How will Person A keep track of these changes?</strong></p>
</blockquote>
<p>Person A and B do one of the above each time A needs to send B money.</p>
 5406: <p>Usually, when people want to pay each other, they are already communicating as they have been arranging some form of transaction. Just like with other settlement methods, the receiver communicates to the sender how they would like to receive payment.</p>
<p>The receiver may do so e.g. by sending an invoice, displaying payment instructions on the checkout page of their merchant website, copying their address into chat, or displaying a QR-code to be scanned with a handheld device.</p>
