Background: Over the last few decades, a search for the theory of protein folding has grown into a full-fledged research field at the intersection of biology, chemistry and informatics. Despite enormous effort, there are still open questions and challenges, like understanding the rules by which amino acid sequence determines protein secondary structure.

Objective: In this review, we depict the progress of the prediction methods over the years and identify sources of improvement.

Methods: The protein secondary structure prediction problem is described followed by the discussion on theoretical limitations, description of the commonly used data sets, features and a review of three generations of methods with the focus on the most recent advances. Additionally, methods with available online servers are assessed on the independent data set.

Results: The state-of-the-art methods are currently reaching almost 88% for 3-class prediction and 76.5% for an 8-class prediction.

Conclusion: This review summarizes recent advances and outlines further research directions.

背景：在过去的几十年中，对蛋白质折叠理论的研究已发展成为生物学，化学和信息学交叉学科的成熟研究领域。尽管付出了巨大的努力，但仍然存在未解决的问题和挑战，例如了解氨基酸序列决定蛋白质二级结构的规则。

目的：在这篇综述中，我们描述了预测方法在过去几年中的进展，并确定了改进的来源。

方法：描述蛋白质二级结构预测问题，然后讨论理论上的局限性，常用数据集的描述，功能以及对三代方法的综述，重点是最新进展。此外，在独立数据集上评估具有可用在线服务器的方法。

结果：目前最先进的方法对于3类预测达到了近88％，对于8类预测达到了76.5％。

结论：这篇综述总结了最近的进展并概述了进一步的研究方向。