Learn in the textbookCoding Conventions and Structuring
DefinitionIndentation (インデンテーション) is simply the English name for 字下げ and refers to exactly the same thing.
ExplanationThe leading space itself, or its width, is called an indent, and one level is made of space characters or a tab. If the width of one level is not kept the same across the whole program, the boundaries between blocks become harder to read, not easier.
Memory hookThe English word indent describes the notch where text is set back inward from the edge of the page.