URI scheme与Windows中protocol术语的准确定义是什么？

Great question—this is one of those terminology mix-ups that trips up a lot of folks, especially when moving between formal URI specs and platform-specific language like Windows uses. Let’s break this down clearly:

Scheme (URI Standard Definition) #

• Per the official URI specification, a scheme is the leading component of a URI (the part before :// or :) that defines the naming and access mechanism for the resource. It sets the rules for how the rest of the URI (authority, path, query, etc.) should be interpreted and processed.
• For example, in http://example.com or mailto:user@domain.com, http and mailto are schemes. The scheme tells the system "use the HTTP protocol to fetch this web resource" or "use the email protocol to handle this address"—but the scheme itself is a formal structural element of the URI standard.
• By spec, schemes are case-insensitive strings starting with a letter, followed by letters, numbers, +, -, or ..

Protocol (Windows' Contextual Term) #

• In Windows, "protocol" is a user-friendly, platform-specific term that maps directly to the URI scheme. It’s used to frame the concept around how the operating system associates different URI schemes with applications.
• When you see "Choose default apps by protocol" in Windows settings, each listed "protocol" corresponds to a URI scheme (like http, ftp, steam). Windows uses this term to make the concept accessible to users: it’s framing the scheme as a "protocol" that your system uses to decide which app opens a given type of link.
• Unlike the formal URI scheme definition, Windows' "protocol" is tied directly to the OS’s application association system—it’s less about the URI structure and more about practical, user-facing behavior.

Quick Summary #

To put it simply:

• Scheme is the formal, standard term for the leading component of a URI, defining the resource access framework.
• Windows' "protocol" is a colloquial, platform-specific alias for URI schemes, focused on the system’s app association logic.

They refer to the same underlying identifiers, but the terms come from different contexts—one from web standards, the other from user-focused OS design.

内容的提问来源于stack exchange，提问作者Maximouse