user4823: Complete example:

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


Breakdown:
Version (4-byte):
01000000

Number of inputs (variable size but in this case it is 1-byte):
01

Previous transaction ID byte swapped (32-byte):
186f9f998a5aa6f048e51dd8419a14d8a0f1a8a2836dd734d2804fe65fa35779

prev_out_index (4-byte):
00000000

scriptSig length (variable size but in this case it is 2-byte which represents 139-bytes for the following scrtiptSig):
8b

scriptSig (variable size but in this case it’s 139-byte):
483045022100884d142d86652a3f47ba4746ec719bbfbd040a570b1deccbb6498c75c4ae24cb02204b9f039ff08df09cbe9f6addac960298cad530a863ea8f53982c09db8f6e381301410484ecc0d46f1918b30928fa0e4ed99f16a0fb4fde0735e7ade8416ab9fe423cc5412336376789d172787ec3457eee41c04f4938de5cc17b4a10fa336a8d752adf

Sequence number: (4-byte):
ffffffff

Don’t know what this is:
02

Value to send (8-byte byte-swapped):
60e3160000000000

Output 1 – Receiving address for amount above:
19 76 a9 14ab68025513c3dbd2f7b92a94e0581f5d50f654e7 88 ac

Value for change (8-byte byte-swapped)
d0ef800000000000

Output 2- Change address for amount above:
19 76 a9 147f9b1a7fb68d60c536c2fd8aeaa53a8f3cc025a8 88 ac

LockTime (4-byte):
00000000

Question:
The bit where I wrote Don’t know what this is, which has the value 02.  I don't know what the purpose of that value is.  What's the purpose of that value?

user48884: 
Don’t know what this is:
02

It's the number of outputs in the transaction.

user21052: The bolded byte in the following raw transaction is the number of outputs (two in this transaction):

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

The Bitcoin.org Developer Documentation has an extended description of the raw transaction format if you'd like more information.

4823: <p><strong>Complete example:</strong></p>

<blockquote>
  <p>0100000001186f9f998a5aa6f048e51dd8419a14d8a0f1a8a2836dd734d2804fe65fa35779000000008b483045022100884d142d86652a3f47ba4746ec719bbfbd040a570b1deccbb6498c75c4ae24cb02204b9f039ff08df09cbe9f6addac960298cad530a863ea8f53982c09db8f6e381301410484ecc0d46f1918b30928fa0e4ed99f16a0fb4fde0735e7ade8416ab9fe423cc5412336376789d172787ec3457eee41c04f4938de5cc17b4a10fa336a8d752adfffffffff<strong>02</strong>60e31600000000001976a914ab68025513c3dbd2f7b92a94e0581f5d50f654e788acd0ef8000000000001976a9147f9b1a7fb68d60c536c2fd8aeaa53a8f3cc025a888ac00000000</p>
</blockquote>

<hr>

<p><strong>Breakdown:</strong></p>

<p>Version (4-byte):</p>

<p><strong>01000000</strong></p>

<hr>

<p>Number of inputs (variable size but in this case it is 1-byte):</p>

<p><strong>01</strong></p>

<hr>

<p>Previous transaction ID byte swapped (32-byte):</p>

<p><strong>186f9f998a5aa6f048e51dd8419a14d8a0f1a8a2836dd734d2804fe65fa35779</strong></p>

<hr>

<p>prev_out_index (4-byte):</p>

<p><strong>00000000</strong></p>

<hr>

<p>scriptSig length (variable size but in this case it is 2-byte which represents 139-bytes for the following scrtiptSig):</p>

<p><strong>8b</strong></p>

<hr>

<p>scriptSig (variable size but in this case it’s 139-byte):</p>

<p><strong>483045022100884d142d86652a3f47ba4746ec719bbfbd040a570b1deccbb6498c75c4ae24cb02204b9f039ff08df09cbe9f6addac960298cad530a863ea8f53982c09db8f6e381301410484ecc0d46f1918b30928fa0e4ed99f16a0fb4fde0735e7ade8416ab9fe423cc5412336376789d172787ec3457eee41c04f4938de5cc17b4a10fa336a8d752adf</strong></p>

<hr>

<p>Sequence number: (4-byte):</p>

<p><strong>ffffffff</strong></p>

<hr>

<p>Don’t know what this is:</p>

<p><strong>02</strong></p>

<hr>

<p>Value to send (8-byte byte-swapped):</p>

<p><strong>60e3160000000000</strong></p>

<hr>

<p>Output 1 – Receiving address for amount above:</p>

<p><strong>19 76 a9 14ab68025513c3dbd2f7b92a94e0581f5d50f654e7 88 ac</strong></p>

<hr>

<p>Value for change (8-byte byte-swapped)</p>

<p><strong>d0ef800000000000</strong></p>

<hr>

<p>Output 2- Change address for amount above:</p>

<p><strong>19 76 a9 147f9b1a7fb68d60c536c2fd8aeaa53a8f3cc025a8 88 ac</strong></p>

<hr>

<p>LockTime (4-byte):</p>

<p><strong>00000000</strong></p>

<hr>

<p><strong>Question:</strong></p>

<p>The bit where I wrote <code>Don’t know what this is</code>, which has the value <code>02</code>.  I don't know what the purpose of that value is.  What's the purpose of that value?</p>
 48884: <blockquote>
<p>Don’t know what this is:</p>
<p><strong>02</strong></p>
</blockquote>
<p>It's the number of outputs in the transaction.</p>
 21052: <p>The bolded byte in the following raw transaction is the number of outputs (two in this transaction):</p>

<blockquote>
  <p>0100000001186f9f998a5aa6f048e51dd8419a14d8a0f1a8a2836dd734d2804fe65fa35779000000008b483045022100884d142d86652a3f47ba4746ec719bbfbd040a570b1deccbb6498c75c4ae24cb02204b9f039ff08df09cbe9f6addac960298cad530a863ea8f53982c09db8f6e381301410484ecc0d46f1918b30928fa0e4ed99f16a0fb4fde0735e7ade8416ab9fe423cc5412336376789d172787ec3457eee41c04f4938de5cc17b4a10fa336a8d752adfffffffff<strong>02</strong>60e31600000000001976a914ab68025513c3dbd2f7b92a94e0581f5d50f654e788acd0ef8000000000001976a9147f9b1a7fb68d60c536c2fd8aeaa53a8f3cc025a888ac00000000</p>
</blockquote>

<p>The Bitcoin.org Developer Documentation has an extended description of the <a href="https://bitcoin.org/en/developer-reference#raw-transaction-format" rel="noreferrer">raw transaction format</a> if you'd like more information.</p>
