diff --git a/glossary.asciidoc b/glossary.asciidoc
index 3ffdf808..e5d9a628 100644
--- a/glossary.asciidoc
+++ b/glossary.asciidoc
@@ -144,10 +144,10 @@ OP_RETURN::
     An opcode used in one of the outputs in an OP_RETURN transaction. Not to be confused with OP_RETURN transaction.
 
 OP_RETURN transaction::
-    A transaction type relayed and mined by default in Bitcoin Core 0.9.0 and later that adds arbitrary data to a provably unspendable pubkey script that full nodes don’t have to store in their UTXO database. Not to be confused with OP_RETURN opcode.
+    A transaction type that adds arbitrary data to a provably unspendable pubkey script that full nodes don’t have to store in their UTXO database. Not to be confused with OP_RETURN opcode.
 
 Orphan Block::
-    Blocks whose parent block has not been processed by the local node, so they can’t be fully validated yet.
+    Blocks whose parent block has not been processed by the local node, so they can’t be fully validated yet. Not to be confused with stale block.
 
 Orphan Transactions::
     Transactions that can't go into the pool due to one or more missing input transactions.
@@ -223,7 +223,7 @@ SPV (aka Simplified Payment Verification)::
     SPV or Simplified Payment Verification is a method for verifying particular transactions were included in a block without downloading the entire block. The method is used by some lightweight Bitcoin clients.
 
 Stale Block::
-    Block which were successfully mined but which isn’t included on the current best block chain, likely because some other block at the same height had its chain extended first.
+    Block which were successfully mined but which isn’t included on the current best block chain, likely because some other block at the same height had its chain extended first. Not to be confused with orphan block.
 
 timelocks::
     A Timelock is a type of encumbrance that restricts the spending of some bitcoin until a specified future time or block height. Timelocks feature prominently in many Bitcoin contracts, including payment channels and hashed timelock contracts.
diff --git a/preface.asciidoc b/preface.asciidoc
index 27b5ec39..0973cab6 100644
--- a/preface.asciidoc
+++ b/preface.asciidoc
@@ -51,7 +51,7 @@ This icon indicates a warning or caution.
 
 === Code Examples
 
-((("code examples, obtaining and using", id="codeuse00")))The examples are illustrated in Python, C++, and using the command line of a Unix-like operating system such as Linux or macOS. All code snippets are available in the Github repository (https://github.com/bitcoinbook/bitcoinbook[https://github.com/bitcoinbook/bitcoinbook]) in the _code_ subdirectory of the main repo. Fork the book code, try the code examples, or submit corrections via GitHub.
+((("code examples, obtaining and using", id="codeuse00")))The examples are illustrated in Python, C++, and using the command line of a Unix-like operating system such as Linux or macOS. All code snippets are available in the GitHub repository (https://github.com/bitcoinbook/bitcoinbook[https://github.com/bitcoinbook/bitcoinbook]) in the _code_ subdirectory of the main repo. Fork the book code, try the code examples, or submit corrections via GitHub.
 
 All the code snippets can be replicated on most operating systems with a minimal installation of compilers and interpreters for the corresponding languages. Where necessary, we provide basic installation instructions and step-by-step examples of the output of those instructions.