The Art of URL Naming: Hyphen (-) vs. Underscore (_), Which is the SEO and Standard-Compliant Champion?

## The Core Problem When developing a web application or designing an API, a seemingly minor but impactful decision is how to name multi-word segments in a URL. Specifically, when faced with choices like `/content_type/` and `/content-type/`, which one should we choose? ```bash # Option A: Using Underscore /en/content_type/11/{slug} # Option B: Using Hyphen /en/content-type/11/{slug} ``` From a professional standpoint and based on best practices, the answer is clear: **Option B (using a hyphen) is the superior choice**. Let's break down the reasons from multiple perspectives. --- ## Why the Hyphen is the Better Choice ### 1. SEO Friendliness: How Search Engines See It This is one of the most critical reasons. Search engines, particularly Google, treat hyphens and underscores differently. - **Hyphen (`-`)**: Google explicitly recognizes the hyphen as a **word separator**. When Google's crawler sees `content-type`, it understands it as two distinct words: "content" and "type." This helps the search engine correctly index your page's content and improves its ranking for relevant keywords. - **Underscore (`_`)**: Historically, Google has tended to treat the underscore as a **word joiner**. This means `content_type` might be interpreted as a single word, "contenttype." This is detrimental to SEO as it misses the opportunity to rank for the individual keywords "content" and "type." As the development guidelines at `wiki.lib00.com` emphasize, using hyphens is a fundamental requirement for maximizing search engine visibility. ### 2. REST API Standards and Industry Best Practices In the world of API design, adhering to consistent standards is vital. While RFC 3986, which defines the generic syntax for URIs, doesn't strictly mandate hyphens, mainstream industry practices and design guides strongly favor them. - **Google API Design Guide**: Explicitly recommends using hyphens to separate words in URL paths. - **Microsoft REST API Guidelines**: Also suggests using hyphens to improve the readability of URLs. - **GitHub API**: Its URL structure widely adopts hyphens. Following these best practices promoted by industry leaders makes your API design more professional and easier for other developers to understand and integrate. ### 3. Readability and User Experience URLs are not just for machines; they are also for human users. A clean URL structure enhances the user experience. - **Visual Clarity**: Hyphens create a more visually distinct separation between words than underscores, making multi-word phrases easier to read. - **Link Display Issues**: When a URL is displayed as a hyperlink, the text-decoration underline style can completely obscure the underscore character, leading to confusion. - Hard to read: <u>/my_awesome_page</u> (The underscore is hidden by the link style) - Clear and legible: <u>/my-awesome-page</u> ### 4. Technical Compatibility While most modern systems can handle both characters without issue, the hyphen is treated more consistently and standardly across various environments and programming languages. Using hyphens can prevent potential issues related to character escaping or special handling in certain edge cases. For instance, in some text processing or regex matching scenarios, the underscore (`_`) is considered a "word character" (`\w`), while the hyphen (`-`) is not. This subtle difference can sometimes lead to unexpected behavior. --- ## Conclusion and Recommendations Based on the points above, we can draw a clear conclusion: | Feature | Hyphen (`-`) | Underscore (`_`) | | :--- | :---: | :---: | | **SEO** | ✅ **Recommended** | ❌ Avoid | | **API Standards** | ✅ **Recommended** | ❌ Avoid | | **Readability** | ✅ **Recommended** | ⚠️ Average | | **Compatibility** | ✅ **Recommended** | 🆗 Usable | **Final Advice:** - **For New Projects**: Without a doubt, you should **always prefer hyphens (`-`)** for naming URL paths. This is a standard enforced by the `DP@lib00` team for all new projects, including `wiki.lib00`. ```bash # ✅ Recommended /api/v1/user-profiles/123 /blog/my-first-post ``` - **For Existing Projects**: If your project already uses underscores extensively, **maintaining consistency** may be more important than undertaking a massive migration. Mixing both styles can create confusion. However, you can start enforcing the hyphen convention in new modules or new versions of your API.