Today's topic is how to format lists.
Numbers are reserved for instances where the items in the list need to follow a specific sequence. You could use numbers to list the step-wise tasks that are required—in order—to start up a piece of machinery, for example. To turn on your old laptop
1. Open the cover.
2. Push the start button.
3. Make tea while all the applications load.
Finally, letters are useful when you're implying that readers need to choose individual items or when items don't need to follow a specific sequence, but you want to refer to an item later. For example, punctuation in lists can be tricky. You have to consider
Letters make sense with that list because the order doesn't matter. Bullets would work just as well, but if you wanted to refer to the items again later, using letters could help readers easily find the list item when they look back through the text. If you mention a letter later in your text, enclose it in parentheses (e.g., Item (b) was about periods.)
You can use capital or lowercase letters for your list, but the typical style is to use lowercase letters. The most important thing is to be consistent.
Letters are also often used when you have a list in which the items don’t need to be in a particular order, but you want to keep them in a sentence instead of listing them vertically. The letters can call extra attention to each list item (5), but if you’re putting in letters to separate list items in a sentence, you should also ask yourself if it might be easier for your readers to digest the material if you listed the items vertically.