diff --git a/episodes/profiling-functions.md b/episodes/profiling-functions.md
index 71ac9e1..b7cf902 100644
--- a/episodes/profiling-functions.md
+++ b/episodes/profiling-functions.md
@@ -73,7 +73,9 @@ def c():
 a()
 ```
 
-Prints the following call stack:
+Here we can see that the printing of the stack trace is called in `c()`, which is called by `b2()`, which is called by `a()`, which is called from global scope.
+
+Hence, this prints the following call stack:
 
 ```output
   File "C:\call_stack.py", line 13, in <module>
@@ -86,7 +88,11 @@ Prints the following call stack:
     traceback.print_stack()
 ```
 
-In this instance the base of the stack is printed first, other visualisations of call stacks may use the reverse ordering.
+The first line states the file and line number where `a()` was called from (the last line of code in the file shown). The second line states that it was the function `a()` that was called, this could include it's arguments. The third line then repeats this pattern, stating the line number where `b2()` was called inside `a()`. This continues until the call to `traceback.print_stack()` is reached.
+
+You may see stack traces like this when an unhandled exception is thrown by your code.
+
+*In this instance the base of the stack has been printed first, other visualisations of call stacks may use the reverse ordering.*
 
 :::::::::::::::::::::::::::::::::::::::::::::
 
diff --git a/learners/reference.md b/learners/reference.md
index 3cb17a2..03d71b7 100644
--- a/learners/reference.md
+++ b/learners/reference.md
@@ -12,6 +12,9 @@ Bottleneck
 
 *Bottleneck is a synonym of limiting factor.*
 
+Call Stack
+: The internal stack data-structure used during the execution of code, that tracks metadata related to the currently executing hierarchy of function calls. Elements in the call stack are referred to as stack frames.
+
 `cProfile`
 : A function level profiler provided by the Python standard library.
 
@@ -29,11 +32,26 @@ Limiting Factor
 `line_profiler`
 : A line level profiler for Python that can be installed via `pip`.
 
+Pop
+: The action of removing the top item from a stack data-structure (sometimes also used in reference to removing and returning the first item from a list or queue).
+
 Profiling
 : The measuring and analysis of granular performance metrics of a program, to understand where time is being spent during execution. Typically used to prioritise optimisation.
 
+Push
+: The action of adding an item to the top of a stack data-structure (sometimes also used in reference to appending an item to a list or queue).
+
+Recursive
+: A recursive function or algorithm is one that calls itself. Too many recursive calls, can lead to stack overflow exceptions. Most recursive functions can be restructured as loops.
+
 `snakeviz`
 : A web-browser based visualisation tool for `cProfile` outputs that can be installed via `pip`.
 
+Stack
+: A last-in-first-out (LIFO) data structure. Similar in nature to a physical stack (e.g. of books), items are added to the top and those below the top cannot be accessed without first removing the ones above them.
+
+Stack Frame
+: The term used to refer to elements within the call stack. A call stack's stack frame will contain metadata about a particular function call, such as where it was called from and any variables that have been allocated 'on the stack' within the function's local scope. When a stack frame is popped from the call stack, any variables allocated within the corresponding function's local scope would be deallocated.
+
 `viztracer`
 : A timeline profiler for Python that can be installed via `pip`.