Greek letters in text without changing to math mode

You don’t need to change to math mode every time you want to type a greek letter in normal text. Loading the textgreek package allows typesetting greek letters, generally just by adding a text-prefix to the letter name, e.g. for it would be:

\usepackage{textgreek}
...
\textDelta\textbeta

The letters will adapt to the font style you are using (bold, italics, small capitals, etc.)

Furthermore, the author provides three different font types, cbgreek (default), euler, and artemisia. The font type can be change through the optional argument, when loading the package:

\usepackage[euler]{textgreek}

The differences are minor for most letters, check the documentation for details.

Complete command list (copied from the documentation):

Note, is an exception. Since the textcomp package already provided a command textmu, the author decided to call it textmugreek instead. Use the latter to avoid unexpected results.