Sub- domain vs. Sub- directory; the argument has been brewing for as long as SEO has been practiced. Of course there are many a personal preference around this topic, all influenced by experience. The biggest difference between the two is that sub- directories explain what pages are about and sub- domains describe individual sites.
- Additional directory within root domain
- Folder within a site
- Used for better organisation of content
General traits of a Sub- directory
- Better for smaller sites
- Builds dominance in one place over time
- Easy to manage (less technical)
- Basic geo- targeting
- Considered part of the same domain by search engine
- Beneficial to use for a blog (hosted on the same domain)
- Numerous sub- directories can be created per domain
- Indexed quickly by search engines
- Organisation (arrange content into descriptive URL’s)
If quality content is missing, it is always better to use the sub- directory route. It is important to try and think like the search engine. Do not use low quality content as search engines will always generate quality results for the user. This means that should the sub- domain feature a lack of work or low quality content, it will not rank as it is suspicious content.
- Requires generous and quality information and content (different content)
- Better for sites that are competitive in various related arenas
- Targets different cities etc more effectively
- Treated as separate website by search engines (including Google)
- Able to add new niches to a domain
- Considered a sub- extension of current domain
- Gain benefits of website (without costs of registering and hosting)
- Hosted on same account as normal domain (shown in a different folder)
It is necessary to create backlinks for sub- domains, as you would for a new site. If the sub- domain becomes banned, it will in- turn, affect the main site as they are linked.
There are benefits and drawbacks to using sub- domains but in the long run and for the most part, there is nothing wrong with using them. Both of the above are useful, In fact using sub- directories on each sub- domain works well too.