Refers to a person at the introductory level of a skill, subject, or activity. Often used in educational or training contexts.
このクラスは初級者向けです。
This class is for beginners.
初級者でも簡単に使えるソフトです。
It's software that even beginners can use easily.
初級者 stresses a low rank within a structured proficiency system (like class levels), while 初心者 more broadly means someone new to any skill.
初級者 specifically marks someone at the elementary skill level in structured learning like language or music classes, whereas ビギナー is a more general, casual term.
Compound of 初級 (beginner level) + 者 (person).