Let $mathcal{C}$ be a triangulated category. We first introduce the notion of balanced pairs in $mathcal{C}$, and then establish the bijective correspondence between balanced pairs and proper classes $xi$ with enough $xi$-projectives and enough $xi$-injectives. Assume that $xi:=xi_{mathcal{X}}=xi^{mathcal{Y}}$ is the proper class induced by a balanced pair $(mathcal{X},mathcal{Y})$. We prove that $(mathcal{C}, mathbb{E}_xi, mathfrak{s}_xi)$ is an extriangulated category. Moreover, it is proved that $(mathcal{C}, mathbb{E}_xi, mathfrak{s}_xi)$ is a triangulated category if and only if $mathcal{X}=mathcal{Y}=0$; and that $(mathcal{C}, mathbb{E}_xi, mathfrak{s}_xi)$ is an exact category if and only if $mathcal{X}=mathcal{Y}=mathcal{C}$. As an application, we produce a large variety of examples of extriangulated categories which are neither exact nor triangulated.
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