A variety of tab_vim techniques in vim

Expandtab: When you type <tab>, you automatically convert <tab> to spaces

Tabstop=n: A <tab> will be converted to n spaces inserted into the text

Retab: When ' Expandtab ' is set, the newly typed <tab> is converted to a space, but the existing <tab> requires the Retab command to be converted.

Shiftwidth=n: Automatically inserts n spaces when indented

Softtabstop=n: If Expandtab is open, type <tab> insert n number of spaces; if Expandtab closes, type <tab> mix into <tab>+<space> Easy to type <bs> Delete