Choosing between a main domain and a subdomain can feel like choosing your favorite ice cream flavor—both are good, but the right choice depends on what you’re looking for. This is especially true when it comes to SEO (Search Engine Optimization) and how users interact with your site. Whether you’re starting a new blog, launching a product, or building a business, understanding the difference can help you make smarter decisions about your web presence.
TL;DR
A main domain is great for consolidating SEO strength and brand identity. A subdomain works well for separate projects, languages, or business segments. Search engines sometimes treat subdomains like separate sites, which can dilute your SEO if not handled well. Use a main domain when possible, and choose subdomains when you need content separation or technical flexibility.
What’s a Main Domain?
A main domain is your website’s primary address. Think of it as your home on the internet. Example? www.example.com is a main domain.
- Brand Identity: It carries your brand’s weight.
- SEO Power: All content under the domain contributes to one SEO profile.
- Better Authority: Google sees main domains as more cohesive.
If you’re starting one main site or brand, using a main domain is usually the best choice.
What’s a Subdomain?
A subdomain is a part of your main domain, but it’s treated kind of like its own room. Example? blog.example.com and shop.example.com.
- It’s often used to separate sections of a business or service.
- Developers like them for testing environments like dev.example.com.
- They’re useful for targeting different regions or languages, like fr.example.com.
Subdomains offer flexibility, but they come with some SEO baggage.
Main Domain vs Subdomain: SEO Showdown
This is where things get spicy. Let’s break it down.
1. Crawling and Indexing
Google’s bots treat main domains and subdomains differently. Subdomains are often seen as separate sites. That means you’ll need to build trust and authority for each one separately.
- Main domain: Everything contributes to one SEO score.
- Subdomain: Each subdomain might need its own SEO juice.
Want to maximize shared SEO power? Stick with a main domain and organize content using folders like example.com/blog instead of blog.example.com.
2. Backlink Benefits
Backlinks are like high-fives from other websites. Main domains get the full handshake. With subdomains, it’s a fist bump at best.
Why? Because search engines often think they’re different sites. That means backlinks to a subdomain usually don’t help the main domain’s authority much.
3. Domain Authority
Think of domain authority as your website’s street cred. When you use a subdomain, you’re kind of starting fresh.
Building domain authority for the main site? Then keep things under one domain to avoid spreading your efforts too thin.
So… When Should You Use a Subdomain?
Let’s not bash subdomains too hard. They have their uses, especially when:
- You’re launching a blog that’s stylistically different.
- You want to completely separate internal tools or platforms (like portal.example.com).
- You have multilingual versions of your site—like de.example.com.
- Your team structure calls for autonomy between product areas.
Sure, you may lose a bit of shared SEO value, but you gain control, flexibility, and maybe even performance improvements.
Real World Examples
Let’s take a peek at what actual companies do.
- Google: Uses subdomains for different services like maps.google.com or mail.google.com.
- Amazon: Keeps most stuff under one domain using folders like amazon.com/gp/help.
- Wikipedia: Uses subdomains for languages: en.wikipedia.org, fr.wikipedia.org, etc.
It’s not about what’s better in general—it’s about what’s better for you.
Subfolders: The Middle Ground
Here’s a handy tip: use subfolders when you want the SEO perks of a single domain but still crave structure.
Instead of blog.example.com, go with example.com/blog.
- Boosts domain authority.
- Easier link-building.
- Better cohesion for Google and users alike.
What Does Google Say?
Google’s official line? They’re fine with either option—as long as your site is structured well and full of useful content.
But savvy SEOs know that it’s often harder to maintain domain authority across multiple subdomains unless you’ve got serious resources.
Translation: most small to medium websites should go with folders under the main domain.
Technical Considerations
SEO is only one part of the puzzle. Let’s throw in some tech talk (don’t worry, we’ll keep it easy):
- Cookies: Subdomains may not share cookies. That affects logins and sessions.
- SSL Certificates: Extra setup may be needed for subdomains.
- CMS Management: Managing multiple subdomains can mean more backend headaches.
Unless you’re running separate teams or products, a main domain just makes life easier.
Checklist: Which One Should You Use?
Still unsure? Here’s a quick checklist to help you decide.
Go With a Main Domain (and subfolders) If:
- You want strong central SEO.
- Your content is related.
- You have one team managing the site.
- You’re focused on brand cohesion.
Go With a Subdomain If:
- You’re targeting different audiences or countries.
- You need different technologies or designs.
- You want isolated areas for testing or development.
- You have separate marketing strategies and teams.
Future-Proof Your Decision
Your choice isn’t set in stone—but changing later can be painful. So think about where your site is going, not just where it is today.
Want SEO power and simplicity? Side with the main domain and its folders.
Want flexibility and separation? Pick subdomains wisely.
Final Thoughts
In the great debate of main domain vs subdomain, there’s no one-size-fits-all answer. It depends on your goals, audience, and resources.
Just remember: subdomains give you space, but main domains give you strength. And when it comes to SEO, strength usually wins!
