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Now when it comes to naming your variables,

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you can pretty much call it whatever it is you want.

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So instead of calling this name,

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I could have just called it n and I could have called this l and as long as I'm

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consistent.

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So if I wanted to get the length of N then I would have to change this as well.

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And if I wanted to print out L then I have to change this as well.

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But there's a couple of rules that you should probably follow.

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And the most important one is to make your code readable. Because if you come

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back to this in six months, 12 months,

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N and L is not going to have a lot of meaning for you.

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So try to make sure that it actually makes sense to you.

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And if you want to,

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you can actually have multiple words in the name of your variable.

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So for example, if you wanted to call this username,

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then you would write the word user and then you would separate each of the words

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with an underscore. But you can't have a space in between.

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This is not valid code and if you try to run it, you'll get a syntax error.

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So the name of the variable has to be one single unit and in order to separate

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words in Python, we use the underscore.

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Now if you want to use numbers in the name of your variable,

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you can. So for example, length1,

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length2. But they can't be at the beginning of the name of the variables.

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You can't say 1length or 3length.

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That will generate a syntax error as well. Finally,

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there's certain privileged words that we use, for example,

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the names of our functions like print and input.

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And it's usually good practice to not use them as the names of your variables

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because you can see that syntax highlighting gets messed up because it thinks

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that is actually input function you're trying to create.

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And even though often when you run your app, it might not have any issues,

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this is really bad practice because it's very confusing.

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So try to make sure that all the names of your variables get highlighted,

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like the other variables in the same color. Now,

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the final thing to remember is that if you decide to call your variable this

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particular name, n-a-m-e, and at a later point you make a typo and you spell it

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wrong, so maybe instead of name you said nama,

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this is not going to work and when you run your code you'll get what's called a

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name error because it says this name is not defined. And the idea is that you

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would look at where the error is, line 2, print nama and you'll see,

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Oh that's not right. It's meant to be spelled n-a-

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m-e. So you'll have to go and fix it in order for your code to work.

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Now remember that this is not because Python is doing any sort of spell-checking

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for you. It's like, Oh, that's not how you spell name. No. In fact,

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if you decided to call this nama and you, later on, used it as name,

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there's no problems, there's no issues, no errors,.

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As long as it's consistent,

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this is the name that's associated with this piece of data. Later on,

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when you want to use this piece of data, you use this name to refer to it.

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And as long as these two spellings are identical,

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then the computer doesn't care at all.

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So when you get a name error in your code,

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you now know it's probably because you've misspelled or mistyped one of the

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variable names somewhere in your code. Now in the next lesson,

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I prepared a quiz for you where you'll get to select which variable names are

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valid and which ones are not good practice.

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Have a go at that over on the next lesson.