By what age do toddlers generally begin to use one-word sentences?

By around 12 months of age, toddlers typically begin to use one-word sentences, also known as holophrastic speech. At this developmental stage, children often communicate their needs and thoughts using single words that can express full ideas, such as "milk" for wanting milk or "up" to indicate they want to be picked up. This is an important milestone in language development, as it shows the child’s growing ability to associate words with their meanings and to express themselves in a more communicative way.

At this age, children are also expanding their understanding of language, although they are still in the early stages of language acquisition. As they approach 18 months and beyond, children will begin to combine words into simple two-word phrases, gradually building a more complex understanding and use of language. Therefore, understanding that 12 months is the typical age for initiating one-word sentence usage is crucial for assessing developmental milestones in toddlers.