many python programmers recommend that each line should be less than characters historicallythis guideline developed because most computers could fit only characters on single line in terminal window currentlypeople can fit much longer lines on their screensbut other reasons exist to adhere to the -character standard line length professional programmers often have several files open on the same screenand using the standard line length allows them to see entire lines in two or three files that are open side by side onscreen pep also recommends that you limit all of your comments to characters per linebecause some of the tools that generate automatic documentation for larger projects add formatting characters at the beginning of each commented line the pep guidelines for line length are not set in stoneand some teams prefer -character limit don' worry too much about line length in your code as you're learningbut be aware that people who are working collaboratively almost always follow the pep guidelines most editors allow you to set up visual cueusually vertical line on your screenthat shows you where these limits are note appendix shows you how to configure your text editor so it always inserts four spaces each time you press the tab key and shows vertical guideline to help you follow the -character limit blank lines to group parts of your program visuallyuse blank lines you should use blank lines to organize your filesbut don' do so excessively by following the examples provided in this bookyou should strike the right balance for exampleif you have five lines of code that build listand then another three lines that do something with that listit' appropriate to place blank line between the two sections howeveryou should not place three or four blank lines between the two sections blank lines won' affect how your code runsbut they will affect the readability of your code the python interpreter uses horizontal indentation to interpret the meaning of your codebut it disregards vertical spacing other style guidelines pep has many additional styling recommendationsbut most of the guidelines refer to more complex programs than what you're writing at this point as you learn more complex python structuresi'll share the relevant parts of the pep guidelines working with lists