됐다 vs 된다 They are the past and present tense -다 (a plain-formal sentence ending) conjugations of the verb 되다. The three common tense forms are: - 된다 - present. Add -ㄴ다 (if stem ends with a vowel) or -는다(with consonant) to the verb stem. - 됐다 (되었다) - past (and present perfect). Add -았/었다 to the stem. - 될 것이다 - future. Add -ㄹ. 될 (tenseless "potential" form) + 것이다 (so it will be) is the future tense form. There are other sentence endings as well. The four common present tense endings are shown below. * -ㅂ니다 (됐습니다, 됩니다) - polite, formal. * -ㄴ다 (됐다, 되다) - plain, formal. * -아/어요 (됐어요, 돼요) - polite, informal). * -아/어 (됐어, 돼) - plain-informal. (되(다) + 아/어 makes 되어, but this form is commonly contracted to 돼. When there's no -아/어, it remains 되) Here are examples of regular and irregular conjugation examples. - 하다 (do) => 한다, 하였다->했다 (*), 할 것이다. ('*' shows irregular cases) - 치다 (hit) => 친다, 치었다->쳤다, 칠 것이다. - 먹다 (eat) => 먹는다, 먹었다, 먹을 것이다. - 묻다 (bury) => 묻는다, 묻었다, 묻을 것이다. - 묻다 (ask) => 묻는다, 물었다 (*), 물을 것이다 (*). - 물다 (bite) => 문다 (*), 물었다, 물 것이다. (*) - 풀다 (unravel, solve) => 푼다, 풀었다, 풀(을) 것이다. (*) There is a staggering amount of information on these topics as they make up the foundation of Korean grammar. You'll need to check the tense-related verb conjugations in grammar books or sites.