As in most programming languages, Python has multiple kinds of errors. ValueError usually refers to an invalid value passed into a function, e.g. if you try to execute the statement int('a'), Python will throw a ValueError ('a' is not appropriate for converting into an integer). TypeError refers to a mismatch in types. (Types are the "kinds" of values, e.g. numbers [integers], decimals [floats], pieces of text [strings], etc.) For example, if you try to add an integer to a string, you get a TypeError. Python throws a NameError if you try to access a non-existent variable. A list of built-in errors can be found in the official Python documentation (https://docs.python.org/3/library/exceptions.html)

@Liam Hayes (https://teamtreehouse.com/liamhayes) Hi! I have a note about @Steven Parker (https://teamtreehouse.com/stevenparker)'s example (especially the second one). When I was trying to wrap my head around this, I could not for the life of me understand why the built-in function for changing something to an int would give a ValueError with a string as opposed to a TypeError. Surely, it's expecting a number, right? Well, no. It isn't. The int() function takes either a number or a string. It can convert the string "21" to the integer 21, but it can't convert "dog" to a number. Thus, it's getting the right type, but it's still not a value that it can convert. This is when we get the ValueError. It's of the right type, but the value is such that it still can't be done. That being said, if we tried to send in something that was neither a string nor a number, it would have generated a TypeError as it is of the wrong type. Hope this helps! :sparkles: edited for additional note In your own custom made functions, you can pass in whatever you want, although ideally, you know what you're passing in. This is not true of built-in functions in Python. When in doubt, check the documentation for the function in question.