These terms are often used interchangeably to describe the general problems of children who are not developing language as expected for their age, although their development in other areas appears to be appropriate. A third phrase often used as a general term is �specific language impairment�. The important distinction to grasp is that between delay and disorder. As children build their ability to use language, their use of sounds in speech, their sentences, their words and what they choose to say all change. In the early stages they can seem to be making mistakes, when what they are really doing is using their existing ability to the full. These mistakes are part of learning. Some are very common and to be expected from all children. The various aspects of language also develop in an orderly way. Children generally learn certain sounds, words and sentences before others. The language of children is described as �delayed� when they continue to make the common mistakes and when their language is developing slowly in the usual order of language development. The language of children who make the rare mistakes or whose language is developing in an unusual order is called �disordered�. Assessment by a speech and language therapist is required for the distinction to be made reliably. It is not always possible in the early stages to say whether a child�s language is delayed or disordered.Early delay may resolve itself � but it may turn out to be a disorder.

This describes a mild or severe delay in the child�s development of language, but once the child�s language does appear, it develops normally in sequence and pattern.

This refers to language development which is not only severely delayed but also atypical and uneven. The disordered nature of their language makes it hard for these children to continue developing it. In addition, they have great difficulty coping with communication and learning at school and home. Language is part of almost every aspect of life. These terms are useful, but they can also be misleading as they seem to refer to children with the same kind of problem. However, there is considerable variety in the pattern and severity of abnormal language development. Language development is made up of a number of different areas, including learning to hear speech sounds, making speech sounds, knowing the meaning of words, using words and knowing how words combine to make different types of sentences. It is usually more helpful to look at the areas where the child is having difficulty and how they affect each other.