What takes place in the conjugation that makes this verb a stem-changing verb

Answer 1

In stem-changing verbs, the stem of the verb changes in certain forms of the conjugation, typically in the present tense and preterite tense. This change is usually due to a vowel change in the stem, which affects the pronunciation and spelling of the verb. Stem-changing verbs often follow a pattern where the vowel in the stem changes from e to ie, o to ue, or e to i in certain conjugations. This vowel change in the stem is what differentiates stem-changing verbs from regular verbs in Spanish.