This is misleading, as DLD is not caused by brain damage.Although the term DLD has been used for many years, it has been less common than the term specific language impairment (SLI), which has been widely adopted, especially in North America. The definition of SLI overlaps with DLD, but was rejected by the CATALISE panel because it was seen as overly restrictive in implying that the child had relatively pure problems with language in the absence of any other impairments. Children with such selective problems are relatively rare, and there is no evidence that they respond differently to intervention, or have different causal factors, from other children with language problems.In the UK education system, the term speech, language and communication needs (SLCN) is widely used, but this is far broader than DLD, and includes children with speech, language and social communication difficulties arising from a wide range of causes.The question of whether to refer to childrens language problems as a disorder was a topic of debate among the CATALISE consortium, but the conclusion was that disorder conveyed the serious nature and potential consequences of persistent language deficits. It is also parallel with other neurodevelopmental conditions and consistent with diagnostic frameworks such as the DSM-5 and ICD-11. Where there are milder or more transient difficulties, language difficulties may be a more appropriate term. Areas of language difficulty
DLD can affect a range of areas of language and the degree of impairment in different areas of language can vary from child to child.
Language disorders occurring with these conditions need to be assessed and children offered appropriate intervention, but a terminological distinction is made so that these cases would be diagnosed as language disorder associated with the main diagnosis being specified: e.g. "language disorder associated with autism spectrum disorder." The reasoning behind these diagnostic distinctions is discussed further by Bishop (2017). Benchmarks for children with developmental language disorder
Common red flags at one year of age:  

No reaction to sound
No babbling
Difficulty feeding
No imitation
Limited use of gesturesAt two years of age:

Makes minimal attempts to communicate with gestures or words
Has not spoken their first words
Difficulty following simple directions
Inconsistent response to "no"At three years of age:

Limited use of speech
Incomprehensible speech
Limited understanding of simple questions
Difficulty naming objects
Frustration related to communicationAt four years of age:

Uses only 3-word phrases
Speech is not understandable to parents
Takes a long time to understand others
Difficulty asking questions and finding words to express thoughtsAt five years of age:

Speaks only in simple sentences
Speech is not understandable to teachers
Difficulty answering questions
Difficulty with complex directions
Difficulty telling stories
Difficulty with peer interactions

Assessment
Assessment will usually include an interview with the childs caregiver, observation of the child in an unstructured setting, a hearing test, and standardized tests of language. There is a wide range of language assessments in English. Some are restricted for use by experts in speech-language pathology: speech and language therapists (SaLTs/SLTs) in the UK, speech-language pathologists (SLPs) in the US and Australia. A commonly used test battery for diagnosis of DLD is the Clinical Evaluation of Language Fundamentals (CELF).