One of the hardest things to do when you’re writing a manuscript is using italics properly.

It’s true. They’re very common in science writing, but not many people learned to use them properly when they were younger. There are lots of rules about proper usage to remember and not everyone has an English grammar manual or style guide sitting on their desk. You might use them for emphasis, or for words in other languages, or even just when writing about mathematics.

Do you remember all the rules? Here I talk about some general cases where you might want to use (or not) italics in your work. Remember that in a lot of cases, lots of journals may have different guidelines, but this can help you get started.

Quotes and emphasis

The urge to use italics for quotations and emphasis is strong. But apply them carefully. Different journals and publications have slightly different rules, but the general consensus is that they aren’t always needed.

 Humanities journals have slightly more flexible rules. In some cases, quotations (if longer passages and separated as a block of text) or emphasis might have italics added by an author. Sometimes words written in foreign languages can be written in italics (many times people use quotation marks). These might all be acceptable in different journals, but a good rule of thumb is to generally be careful in these cases.

The titles of books, periodicals, and newspapers should always be in italics. For example, “I would like to be published in The New York Times” would be correct. These italics make it clear to the reader that the author is talking about a publication. If you don’t use them, an idea might be unclear. Take a look at these two sentences:

“As found in Nature.” (the natural environment)

“As found in Nature.” (the publication)

The sentences are almost identical, but the italics make a big difference. “Nature” does not need to be capitalized in the first example, but people often will. This is a discussion for a different day, though.

Using italics for Latin terms

This is one of the most common questions “Do you use italics with Latin or not?” With Latin, there are a lot of different answers to this question. In many cases, it really depends on the journal. How to use italics might change on a case by case basis. In some journals putting Latin in italics is fine but other cases it isn’t done. Because Latin that has been commonly used in English for a long time is usually not in italics. Terms like “etc.” (or et cetera when spelled in full) and “et al.” don’t need to be in italics. Other very common examples are:

• “in vitro” / “in vivo” / “ex vivo”
• “a priori” and “a posteriori”
• “ca.” or “c.” and “vs.” or “v”.
• etc.

There are cases where some specific Latin terms need to be in italics. The names of a genus, species, and subspecies, as well as a variety of names of animals, plants, and microorganisms should be in italics. The common dog, Canis familiaris, and the genus Canis are both in italics. So is the bacterium Escherichia coli. From time to time, you might even see muscle groups in italics. Like I mentioned in our article on easy manuscript editing tips, it’s important to remember to be consistent with your terms! Don’t use “etc”, “etcetera”, “etc.”, and “et cetera” in the same paper (remember, the correct one has a period, “etc.“).

Pro tip: When you are using “e.g.” and “i.e.”, remember to put a comma before and after the term. An example sentence might be, “Fruit, e.g., apples and bananas, are good for you!”

Genes and proteins

In articles that discuss genes (and often proteins), it’s important to remember that genes are in italics, and proteins are not. This can be very challenging, but there are many available resources that can help you in this case. For example, if you need to know about human genes, you can look at the HUGO Gene Nomenclature Committee website for information. There are many resources, so we won’t go over them here today.

Keeping track of all the terms you need to verify can be hard. Make sure that you keep a list of all the genes and proteins in your work so that, when you review your manuscript, you can use the “search” function in MS Word (“Ctrl + F” on a PC, and on a Mac you can use “command + F, or you can just use the search bar at the top right of the page). Go through your document and check all the terms, one by one. Remember that not all genes follow the same rules. Verify by checking with the style guide of the journal you’re planning to submit to (for example, MDPI’s style guide is available here).

Variables

While specific subjects have specific rules, variables are almost always in italics.

If you’re talking about p-values, or sample sizes, for example, p and n are in italics. T is used for temperature and plane P should be in italics. The list of cases for variables is really long but this is why it is important to double check a style guide. ACS, Chicago, etc., all might have slightly different ways of addressing variables, but as many scientific journals use the American Chemistry Society style guide, I’ll provide a few examples here:

• Axes (y axis and x axis, for example).
• Lewis numbers (Le)
• Mach number (Ma)
• Constants (such as g, the acceleration of gravity)
• The list goes on!

There are some specific fields of research (econometrics, mathematics, crystallography, etc.) that have rules for when you should and shouldn’t use italics. But the points listed above are fairly common.

Need more help?

With so many different kinds of subject matter, there are always exceptions. Stay tuned for more information about italics coming soon! We have further reading on the subject of editing your work, including this topic. See here for another list with a few examples! If you still need help with your work, visit the MDPI Author Services page for a free estimate and let us improve your paper (italics included)!