In this tutorial, you will learn about keywords (reserved words in Python) and identifiers (names given to variables, functions, etc.).
Keywords are predefined, reserved words used in Python programming that have special meanings to the compiler.
We cannot use a keyword as a variable name, function name, or any other identifier. They are used to define the syntax and structure of the Python language.
All the keywords except
None are in lowercase and they must be written as they are. The list of all the keywords is given below.
Looking at all the keywords at once and trying to figure out what they mean might be overwhelming.
Identifiers are the name given to variables, classes, methods, etc. For example,
language = 'Python'
language is a variable (an identifier) which holds the value
We cannot use keywords as variable names as they are reserved names that are built-in to Python. For example,
continue = 'Python'
The above code is wrong because we have used
continue as a variable name.
Rules for Naming an Identifier
- Identifiers cannot be a keyword.
- Identifiers are case-sensitive.
- It can have a sequence of letters and digits. However, it must begin with a letter or
_. The first letter of an identifier cannot be a digit.
- It’s a convention to start an identifier with a letter rather
- Whitespaces are not allowed.
- We cannot use special symbols like !, @, #, $, and so on.
Some Valid and Invalid Identifiers in Python
|Valid Identifiers||Invalid Identifiers|
Things to Remember
Python is a case-sensitive language. This means,
variable are not the same.
Always give the identifiers a name that makes sense. While
c = 10 is a valid name, writing
count = 10 would make more sense, and it would be easier to figure out what it represents when you look at your code after a long gap.
Multiple words can be separated using an underscore, like