1 00:00:00,740 --> 00:00:07,160 When you are using variables in Python, you need to adhere to a few rules and guidelines. 2 00:00:07,280 --> 00:00:10,370 Breaking some of these rules will cause errors. 3 00:00:10,400 --> 00:00:17,810 Other guidelines just help you write code that's easier to read and understand, so be sure to keep 4 00:00:17,810 --> 00:00:19,520 these rules so. 5 00:00:19,550 --> 00:00:20,840 Variable names. 6 00:00:20,870 --> 00:00:22,310 Variable names. 7 00:00:22,310 --> 00:00:28,590 So variable names can contain only letters, numbers and underscores. 8 00:00:28,610 --> 00:00:32,450 Here, variable names can contain only letters. 9 00:00:34,770 --> 00:00:35,940 Numbers. 10 00:00:37,730 --> 00:00:39,530 And underscores. 11 00:00:40,470 --> 00:00:45,990 They can start with a letter or an underscore, but not with a number. 12 00:00:45,990 --> 00:00:53,550 So as I said, variable names cannot start with number. 13 00:00:53,550 --> 00:00:56,320 So here, let's try this one. 14 00:00:56,340 --> 00:00:57,150 Var. 15 00:00:58,110 --> 00:00:58,610 Here. 16 00:00:59,770 --> 00:01:01,240 As you can see here, Rozelle. 17 00:01:01,620 --> 00:01:02,080 Rozelle. 18 00:01:02,140 --> 00:01:05,380 And in the end of statement expected. 19 00:01:05,500 --> 00:01:11,260 So as you can as you can see here, we are getting an error because variable names cannot start with 20 00:01:11,260 --> 00:01:12,100 a number. 21 00:01:13,000 --> 00:01:22,690 So, for example, you can also call this message one, it's okay, but you cannot call one message. 22 00:01:23,050 --> 00:01:24,580 Actually, let's try this here. 23 00:01:25,360 --> 00:01:26,550 Message one. 24 00:01:26,560 --> 00:01:28,660 As you can see, we are getting no errors. 25 00:01:28,660 --> 00:01:29,920 But you cannot. 26 00:01:29,920 --> 00:01:30,550 Right? 27 00:01:30,580 --> 00:01:37,030 Name your variable one message or one message without underscore. 28 00:01:38,320 --> 00:01:43,870 Here and spaces are not allowed in variable names. 29 00:01:43,870 --> 00:01:45,700 So here, message here. 30 00:01:45,700 --> 00:01:46,660 Let's write this. 31 00:01:46,690 --> 00:01:47,530 My message. 32 00:01:47,530 --> 00:01:53,970 And here this is a this is okay variable name, but we make space here. 33 00:01:53,980 --> 00:01:55,660 We will get an error. 34 00:01:56,890 --> 00:01:57,940 Instead of using space. 35 00:01:57,940 --> 00:02:01,570 You can also use underscores and you will get no errors here. 36 00:02:02,350 --> 00:02:07,420 Avoid using Python keywords and function names as variable names. 37 00:02:07,420 --> 00:02:08,080 For example. 38 00:02:08,080 --> 00:02:12,070 Do not use the word print as a variable name. 39 00:02:12,280 --> 00:02:18,400 Python has a reserved for a particular programming and programmatic purpose. 40 00:02:19,260 --> 00:02:23,940 And the variable names should not be short but descriptive. 41 00:02:23,970 --> 00:02:31,590 For example, the name is better than N right and the student name here. 42 00:02:31,590 --> 00:02:39,450 Student name is better than student name is better than s n here. 43 00:02:39,450 --> 00:02:40,020 Right. 44 00:02:40,230 --> 00:02:41,100 So. 45 00:02:42,710 --> 00:02:44,450 And name length. 46 00:02:44,480 --> 00:02:49,640 Name length is better than length. 47 00:02:51,020 --> 00:02:52,460 Length. 48 00:02:53,000 --> 00:02:55,010 Of length. 49 00:02:56,730 --> 00:02:57,990 A person's. 50 00:02:59,520 --> 00:03:00,690 Person's name. 51 00:03:01,750 --> 00:03:13,720 And also be careful when using the lowercase letter L and uppercase letter L, because they will. 52 00:03:13,720 --> 00:03:16,930 They could be confused with the numbers one and zero. 53 00:03:18,840 --> 00:03:23,820 It can take some practices to learn how to create good variable names, especially as your programs 54 00:03:23,820 --> 00:03:29,310 become more interesting and complicated as you write more programs and start to read through other people's 55 00:03:29,310 --> 00:03:33,780 code, you will get better at coming up with meaningful names.