Ichidan (one-row) conjugation: a conjugation where only one vowel row changes after the stem. In modern Japanese it appears in verbs like "miru" (to see) and "taberu" (to eat); many end in -iru or -eru, though there are exceptions.
見るは一段活用の動詞で、見ない・見ます・見たのように活用する。
"Miru" is an ichidan verb; it conjugates as miranai, mimasu, mita, etc.
多くの一段動詞は語尾が -る を取り除くだけで活用できるため、学習者にとって覚えやすい。
Many ichidan verbs conjugate simply by removing the final -ru, so they are easier for learners to remember.
ただし、語尾が -iru / -eru の動詞すべてが一段活用というわけではなく、例外もある。
However, not all verbs ending in -iru / -eru are ichidan verbs; there are exceptions.