Create unnumbered Chapters

Question

I want to have chapters in my book that have no number. This means it doesn't show up on the TOC and it also becomes a prefix before a section. It would look like this:

EDIT: the it refers to the number. So I want no chapter number but I do want the chapter title to show up on the TOC. The image is of the TOC.

Answer 1

Use \chapter* (which won't be put into the ToC) instead of \chapter and change the \section numbering to not include a number based on \chapter .

\documentclass{book}
\makeatletter
  \renewcommand*{\thesection}{\@arabic\c@section}
\makeatother
\begin{document}
\tableofcontents
\chapter*{Vay}
  \section{one}
  \subsection{subsection}
  \section{two}
\chapter*{Woohoo}
  \section{three}
  \subsection{subsection}
\end{document}

EDIT:

The above solved what I thought was the OP's problem but then the OP clarified the question.

\documentclass{book}
\usepackage{chngcntr}
\renewcommand{\thechapter}{} % from @JLeonV answer
\counterwithout{section}{chapter} % don't reset section numbers by chapter
\begin{document}
\tableofcontents
\chapter{Vay}
  \section{one}
  \subsection{subsection}
  \section{two}
\chapter{Woohoo}
  \section{three}
  \subsection{subsection}
\end{document}

The above will produce unnumbered \chapter's in the ToC and body of the document with \section and below numbered continuously.

Answer 2

A quick way to do this is to redefine the format of the chapter counter is displayed, with the next code.

\renewcommand{\thechapter}{}