I would like to learn this type of fonts in latex. I have tried all the math fonts but it does not seem to be ana appropriate one. So my question is:what the name of this font in latex?

Answer of Heiko Oberdiek
The question is already closed, thus I have to use the question for the answer; images cannot be put in comments.
Comparison of the image in the question
and the typewriter font of Computer Modern (or EC or Latin Modern):
\documentclass{article}
\begin{document}
\texttt{age=25 AND name=`Bob'.}
\end{document}
Together with the original in black and the \texttt variant in red:
\documentclass{article}
\usepackage{graphicx}
\usepackage{color}
\begin{document}
\leavevmode
\raise.8pt\rlap{\includegraphics[width=50mm,trim=0 0 -.7pt 0]{age25.png}}%
\textcolor{red}{\includegraphics[width=50mm]{age25-cm.pdf}}%
\end{document}
The thickness is quite correct.
However the space between the ' and . is smaller.
Next idea: the . is not set in a fixed-width font:
\documentclass{article}
\begin{document}
\texttt{age=25 AND name=`Bob'}.
\end{document}
Comparison with this variant yields:
\documentclass{article}
\usepackage{graphicx}
\usepackage{color}
\begin{document}
\leavevmode
\raise1pt\rlap{\includegraphics[width=50mm,trim=-.25pt 0 -1.25pt 0]{age25.png}}%
\textcolor{red}{\includegraphics[width=50mm]{t-crop.pdf}}%
\end{document}
Result: \texttt{age=25 AND name=`Bob'}. (cmtt or lmtt)






\texttt{<Your text>}– percusse Jun 11 '14 at 08:39tiniestfontever, from that very, very, very, very tiny screen shot;-)... Seriously, it looks like typewriter font, created with\texttt{...}– Jun 11 '14 at 08:41