ADD stands for Attention Deficit Disorder, an older term historically used to describe a condition characterized primarily by difficulties with attention and concentration without the hyperactivity component. It focused on symptoms such as inattention, distractibility, and poor working memory

. ADD is no longer an official medical diagnosis. Since 1987, the term ADHD (Attention Deficit Hyperactivity Disorder) has been used instead, encompassing three subtypes:

• Predominantly inattentive type (often still colloquially called ADD)
• Predominantly hyperactive/impulsive type
• Combined type (both inattentive and hyperactive/impulsive symptoms)

In practice, ADD typically refers to what is now called the inattentive subtype of ADHD, where hyperactivity is not present or minimal. People with ADD often have trouble focusing, organizing tasks, following instructions, and may appear forgetful or easily distracted

. The change from ADD to ADHD was made to better reflect the range of symptoms and to unify the diagnosis under one term. However, many still use "ADD" informally to describe inattentive symptoms without hyperactivity

. In summary, ADD is an outdated term for what is now classified as the inattentive type of ADHD, a neurodevelopmental disorder involving difficulties with attention and executive function