expandtab

Expandtab is a configuration option in many text editors and development environments that determines how the editor handles tab characters. When expandtab is enabled, pressing the Tab key inserts spaces instead of a literal tab character. When it is disabled, the Tab key inserts an actual tab character. The exact number of spaces or the width of a tab can depend on other settings such as tab width and indentation rules in the editor.

In Vim, the expandtab option toggles this behavior. With expandtab set, Tab inserts spaces to reach the next tab stop, while with it off, Tab inserts a real tab character. The precise appearance of indentation also depends on related settings such as tabstop, shiftwidth, and softtabstop, which control tab width and indentation amount. Different editors use different terminology, but the core idea is similar: convert tabs to spaces for consistent rendering across environments or preserve tabs for compatibility with tools that expect them.

Other editors and IDEs offer comparable functionality, often labeled as “Replace tabs with spaces” or “Convert tabs to spaces.” Some environments provide more granular control over how many spaces a tab represents and how backspacing interacts with spaces versus tab characters. In many coding standards, using spaces (expandtab) is preferred to ensure consistent indentation across editors and viewers.

Choosing whether to enable expandtab depends on project conventions and personal workflow. Enforcing a consistent indentation strategy can improve readability and reduce formatting differences during code collaboration.