Equalizer (Category Theory)

In category theory, an equalizer of two morphisms $f,g:a\to b$ is a morphism $h:c\to a$ such that $f\circ h=g\circ h$. It can be considered the solution to a certain equation $fx=gx$.

This is exactly a limit of the diagram,

\usepackage{tikz-cd}
\begin{document}
\begin{tikzcd}
a \arrow[bend left]{r}{f} \arrow[bend right]{r}[swap]{g} & b
\end{tikzcd}
\end{document}