1.8 URL structure & internationalisationLowVerified
Underscores instead of hyphens
What it is
word_word instead of word-word.
Why it matters
Google treats hyphens as word separators; underscores join words.
How to fix it
Use hyphens.
Impact
Low. Direct.
Evidence
Use hyphens to separate words in URLs. Google Search Central, Keep a simple URL structure