If you’re a native English speaker, you probably don’t think about individual letters too often. Why would you? You use them pretty much automatically. So if I asked you to talk about the letter s, you might not have much to say. But for people who have to learn English, it’s quite important, and can prove to be a tricky little customer.

The first area of confusion is with plurals. Most languages don’t add s to make a plural, like English does, so it can be very hard for speakers of those languages to remember to add the s. Even when some languages do add an s, it’s in a slightly different way. Portuguese and Spanish, for example, often add an s to a noun to make it plural. But, they also add an s to adjectives describing those nouns, leading a lot of Portuguese and Spanish speakers to do the same thing in English. French is similar, but the s is generally silent, meaning that a lot of French speakers don’t pronounce it even if they write it.

But the most common area of error is with third-person singular verbs. That might sound like gibberish, but let me demonstrate:

I walk to work. (first-person singular)

You walk to work. (second-person singular)

He walks to work. (third-person singular)

You’ve possibly never even thought about how we add that s before, as you pick up the habit of doing so at a very young age. But it doesn’t come naturally to non-native speakers. You can probably think of examples of people you know who’ve learnt English, and even if they’re at a high level, they might still say things like He work in the same place as me.

So what’s the story with this s?It’s all about inflection. Most European languages are inflected, which means that words are modified to indicate different grammatical categories such as aspect, person, time, plurality etc. When we change a verb to indicate which person we’re referring to, we call that conjugation. You probably remember doing that if you had to learn a second language in school and, if you’re a native speaker, finding it confusing because in English we only have to conjugate verbs once: for the third-person singular form. And all we do is add an s (or es). Simple! If you ask a lot of English learners what they find easiest about learning English, it’s that they don’t have to learn lots of different verb endings.

Which is great, but the downside is that because you don’t have to think about different verb forms, you forget to change it in the one instance when you do have to conjugate the verb. And that’s compounded by the fact that the change is so small and hard to notice, it’s quite easy to forget.

So why does it still exist? Like other languages, English used to have more verb endings. When you hear people parody Ye Olde English, they say things like  Goest thou to the jousting tourney? or He hath gone to the tourney because they were among the verb endings that existed in Middle English. But as is so often the case, the language got simplified and standardised over many years, until only the s remained. My hunch as to why it’s remained is that it made it easy to distinguish between plural singular. For the first person (I singular, we plural) it’s normally clear from the context if I’m talking about myself or a group of people, especially if I’m not with a group of people. Ditto for the second person (you, you) as we can indicate clearly if we’re addressing just one person or a group. But with the third person it’s not so clear because we’re generally not talking about people who are present, and it might not be obvious to our listener, especially if they didn’t catch the start of the sentence. So we say He goes to work at eight, and They go to work at eight.

Still though, it’s not super crucial to make that distinction, so I think that we might lose the third-person s in time, especially as more and more non-native speakers become proficient in English. Will I miss it if it does disappear? Not really. It won’t affect communication much, and most learners of English will be happy to see it go. But don’t take your s‘s for granted. They might not be around much longer, so appreciate them while they’re here.