Time Expressions & Verb Endings — I can use common time expressions to talk about past, present, and future events using appropriate verb endings at an introductory level.

Every language needs a way to anchor events in time, and Korean is no exception. When you say something happened yesterday, is happening now, or will happen tomorrow, you rely on two tools working together: time expressions (words like 어제, 오늘, 내일) and verb endings that change the tail of the verb to signal tense. Understanding how these two elements evolved helps you see why Korean grammar works the way it does today.

So here is the core question this lesson answers: how do you take a Korean verb stem and attach the right ending so that your listener knows when something happens — and how do common time words reinforce that message? By the end, you will be able to form past, present, and future sentences with confidence.

Before diving into conjugation, you need to understand a few foundational ideas that make Korean tense work. Korean is an agglutinative language, which means you build meaning by stacking suffixes onto a verb stem, almost like snapping LEGO bricks together. Tense is just one of those bricks. Time expressions act as signposts that tell your listener which part of the timeline you are talking about, while verb endings confirm it grammatically.

The diagram above is your roadmap for this entire lesson. Notice that Korean, unlike English, places the verb at the very end of the sentence. The time expression typically comes first, acting as a signpost so your listener immediately knows the time frame. Then the verb ending at the tail confirms it. This double-confirmation system means that even if someone misses the time word, the verb ending still carries the tense information — and vice versa.

Step-by-Step Conjugation Process

Korean verb conjugation follows a predictable pattern once you know the rules. Every verb in the dictionary ends in 다. To conjugate, you first remove 다 to get the verb stem. Then you apply vowel harmony to choose the correct ending variant. The rule is straightforward: if the last vowel of the stem is ㅏ or ㅗ (bright vowels), use the 아 variant; otherwise, use the 어 variant. For the verb 하다 (to do), the special contraction 해 is always used.

Time expressions in Korean function like labels that you place at the start of a sentence. They do not change form depending on the verb — they stay the same every time. The table below organizes the most common ones by tense so you can build your vocabulary systematically.

Let's say you want to tell a Korean friend three things: what you did last weekend, what you are doing today, and what you will do next weekend. We will use the verb 보다 (to see/watch) and the topic marker 저는 (I, polite) to build complete sentences.

If you are coming from English, Korean tense might feel simpler in some ways and trickier in others. English uses auxiliary verbs ("will," "did") and changes word order for questions, while Korean keeps the same word order and modifies only the verb ending. However, Korean adds the layer of vowel harmony, which English does not have. The table below highlights the most important contrasts.

The three basic tenses you have learned in this lesson are the foundation, but Korean grammar goes much deeper. As you advance, you will encounter additional layers that let you express more nuanced time relationships. The table below gives you a preview of where this introductory knowledge leads.

Don't worry about mastering all of these right now. The important thing is that the verb stem + ending pattern you are learning today stays the same at every level. Advanced forms simply insert additional suffixes between the stem and the politeness ending. Think of it as adding more cars to the train — the engine (stem) and caboose (요) stay the same.