When my son was 18 months old and had maybe 4 words, I spent a lot of time on the internet at midnight reading about speech delay. He got a speech therapy referral, we did the work, and at 4 he talks so much I sometimes fantasize about a volume control. A speech delay is when a child is not meeting expected language milestones for their age. It is one of the most common developmental concerns in toddlers affecting around 1 in 5 children. Signs of possible speech delay: fewer than 6 to 10 words by 18 months, not combining two words by 24 months, difficult to understand even by family members by age 3, not pointing or using gestures, not responding to their name consistently, losing words they previously used. Common causes include hearing loss which should always be ruled out first, family history of late talkers, premature birth, chronic ear infections affecting hearing, and being raised bilingual. If you are concerned, request a hearing test first then a speech and language therapy evaluation. Early intervention really works. The earlier support begins the more effective it is. Being a late talker does not predict intelligence or success. Many late talkers catch up completely.