What it is
Google treats hyphens as word separators but does not split on underscores, so word_word can read as a single token. Hyphens are the safe choice for word breaks in URLs. word_word instead of word-word. Google treats hyphens as word separators; underscores join words.
Why does underscores instead of hyphens matter for AI search?
Google treats hyphens as word separators; underscores join words.
How do you fix it?
Use hyphens.
How do you find it on your site?
- Scan URLs for underscores between words.
- Decide which matter enough to change.
- Use hyphens for new URLs and slugs.
- Redirect any underscore URLs you migrate.
Which ranking and citation factors does it touch?
This is a minor parsing nicety rather than a strong factor, but hyphens make the words in a URL legible to Google.
What is the impact?
Low. Direct.
What is the evidence?
Use hyphens to separate words in URLs. Google Search Central, Keep a simple URL structure
Frequently asked questions about underscores instead of hyphens
What does "Underscores instead of hyphens" mean?
word_word instead of word-word.
How do you fix underscores instead of hyphens?
Use hyphens.