Jeff对此有一些想法:https://blog.codinghorror.com/of-spaces-underscores-and-dashes/

两者都有缺点。我建议你选择一个并保持一致。

谷歌过去没有将下划线作为单词分隔符，我认为这很疯狂，但现在显然有了。由于这段历史，破折号是首选。尽管从搜索引擎优化的角度来看，下划线现在是允许的，但我仍然认为破折号是最好的。

一个好处是，一般不懂电脑的上网用户更有可能在键盘上输入破折号，他们甚至可能不知道下划线是什么。

一些较老的web主机和DNS服务器实际上在解析url的下划线时存在问题，所以这可能是这些约定的一部分。

我更喜欢破折号，因为下划线可能在一定程度上被链接下划线所掩盖。文本url主要是为了一眼就能识别出来，而不是为了语法正确，所以保留破折号用于连字符的论点是有限的。

文本URL的准确性很重要的是在将其读给某人时，在这种情况下，您不希望将下划线与空格混淆(反之亦然)。

我还发现破折号更美观，如果这有意义的话。

I'm more comfortable with underscores. First of all, they match in with my regular programming experience of variable_names_are_not-subtraction, second of all, and I believe this was mentioned already, words can have hyphens, but they do not ever have underscores. To pick a really stupid example, "Nation-state country" is different from "nation state country". The former translates something like "the land of nation-states" (think "this here is gun country! Best move along, y'hear?"), whereas the latter looks like a list of sometime-synonyms. http://example.com/nation-state-country/ doesn't appear to mean the same as http://example.com/nation-state_country/, and yet, if hyphens are delimiters/"space"s in addition to characters in words, it can. The latter seems more clear as to the actual purpose, whereas the former looks more like that list, if anything.

URL中允许有空格，所以你可以在链接中使用“/about us”(尽管这将被编码为“/about%20us”)。但老实说，这永远是个人偏好，所以这里没有真正的答案。

我会按照惯例，破折号可以出现在单词中，所以空格应该转换为下划线。