diff --git a/docs/concepts/isis-fundamentals/error-dictionary.md b/docs/concepts/isis-fundamentals/error-dictionary.md
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@@ -0,0 +1,42 @@
+# Error Dictionary
+
+## Introduction
+
+ISIS categorizes errors into four different types to indicate their sources. 
+
+## Unknown Error
+
+This error category encompasses errors that fall outside the scope of User, Programmer, or I/O Errors as listed below. It's typically the most common error and is displayed as a generic error.
+
+Example:
+```
+**ERROR** Unable to find PVL group [SearchChip].
+```
+
+## User Error
+
+This error occurs when users select invalid values for input parameters. Examples include entering a negative integer for a parameter that only allows positive integers, mistyping parameters, or inputting a value not in a required list (such as 8-bit, 16-bit, or 32-bit). Typically, this error is associated with user input provided either in the ISIS graphical user interface (GUI) or via the command line.
+
+Example:
+```
+**USER ERROR** Unknown parameter [to].
+```
+
+## Programmer Error
+
+This particular error is uncommon, arising when the programmer provides invalid information to a C++ class and/or method. Typically, these errors are detected by the programmer during the software development phase. They might occur in exceptional situations like array out-of-bounds or memory leaks. Users encountering these errors should open an issue in the [ISIS Repository](https://github.com/DOI-USGS/ISIS3/issues).
+
+Example:
+```
+**PROGRAMMER ERROR** Cannot compare a invalid angles with the < operator.
+```
+
+## I/O Error
+
+File I/O errors encompass operations such as opening, closing, reading, or writing files. These errors may involve: 1) attempting to access a non-existent file upon opening or allocation, often due to misspellings or incorrect directory paths, 2) encountering read and/or write permission issues stemming from user or group ownership, and 3) facing inadequate disk space for allocating an output file.
+However, these errors do not pertain to cases where a file lacks the expected values inside it, such as reading a corrupted PVL.
+
+Example:
+```
+**I/O ERROR** Unable to open [test.cub].
+```
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diff --git a/mkdocs.yml b/mkdocs.yml
index bbbc7e956fa358b980cb85ebb7fb46ed7c26bb22..f291b3eda56bcbe4ca37fcea14a11d45787865cb 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -90,6 +90,8 @@ nav:
       - Special Pixels:                    concepts/isis-fundamentals/special-pixels.md
       - Command Line Usage:                concepts/isis-fundamentals/command-line-usage.md
       - Preference Dictionary:             concepts/isis-fundamentals/preference-dictionary.md
+      - Error Dictionary:                  concepts/isis-fundamentals/error-dictionary.md
+
     - SPICE:
       - SPICE Overview:                            concepts/spice/spice-overview.md
       - SPICE Position Functions and Requirements: concepts/spice/spice-position-functions-and-requirements.md