[Tex/LaTex] How to write Definition 2.1. in texmaker

Question

I am just want to write Defintion 2.1. in texmaker ? I already used

\subsection
\begin{definition}
\end{definition}  

but I can't found the output Definition 2.1. so please kindly tell us.

After writing Definition 2.1 by followed the answer here. I'm want to write Remark 2.1. as given the below answer but my output is Remark 2.2. so please do help me to write Remark 2.1.

Answer 1

May be this:

\documentclass{article}
\usepackage{amsthm}
\newtheorem{definition}{Definition}[section]    %% this does it
\begin{document}
  \section{Some}
  \section{some other}
  \begin{definition}
    Some definition
  \end{definition}
\end{document}

Or this:

\documentclass{article}
\usepackage{amsthm}
\newtheorem{definition}{Definition}[subsection]
\begin{document}
  \section{Some}
  \section{some other}
  \subsection{Some}
  \subsection{Other}
  \begin{definition}
    Some definition
  \end{definition}
  \begin{definition}
    Some other definition
  \end{definition}
\end{document}