You use them every day, but do you know what those abbreviations actually stand for? Derived from the Latin word brevis, meaning short, abbreviations are largely a 20th-century phenomenon, whether you’re looking at pronounceable acronyms (like POTUS or NASA) or initialisms (like FYI or FAQ).

While abbreviations are peppered through today’s modern text speak (including the ubiquitous "lol") there are several other common abbreviations that go way back to ancient Latin origins. Here’s what they are – and what they stand for.

E.g.

A great number of abbreviations come from Latin, which is why they’re abbreviated today, since most of us aren’t fluent in this dead language. E.g. stands for exempli gratia and means, quite simply, "for example." You may use it to spark inspiration, such as saying, “I’d like to see some unique themes for prom, e.g. Under the Sea or Murder Mystery.”

I.e.

Although quite a few people use e.g. and i.e. interchangeably, they do mean something different. I.e. means id est, which translates into "in other words." Compared to e.g. the use here is to provide some subtext or clarity to whatever you’re saying, such as, “There’s just not room in the budget this year, i.e. ask again in three months.”

Etc.

Yet another Latin abbreviation, this one is shortened from et cetera, which means "left over," or "the rest." It’s used to avoid spelling out an entire list by highlighting a few basic examples. You could say, “We need to go shopping for pizza toppings like cheese, tomato sauce, mushrooms, etc.”

Et al.

Similar to etc., but a little more specific, is the Latin abbreviation et al., short for et alia (neutral plural), as well as et alii (masculine) and et aliae (feminine). When you use the abbreviation you don't need to worry about which one to use. All of these mean the same thing: "and others." It’s commonly used to describe multiple contributors to a written or other creative work. For example, you could say, “The song ‘Shallow’ was written by Lady Gaga, Mark Ronson, et al.” While et al. is meant only to be used for citations, some people do use it in a similar way to etc.

B.C. / A.D.

History buffs will likely already know the meaning of these two acronyms. B.C. means before Christ, while A.D. stands for anno Domini, which translates into in the year of the master. Both of these terms are used in calculating the Julian and Gregorian calendars (AKA the most widely used calendars in the world), with A.D. counting the years after Jesus of Nazareth is thought to have been born. Many modern historians, however, have adopted B.C.E. and C.E. which stand for "Before Common Era" and "Common Era" respectively and serve as secular abbreviations for the marking of time.