Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex, debilitating disease that is classified as a neurological condition by the World Health Organization (WHO).
Around 25% of people who have ME/CFS are so unwell they are housebound or bedbound.
The condition affects many body systems including the immune and cardiac systems, and cellular energy production.
People living with ME/CFS experience many symptoms such as profound and disabling fatigue, sleep disturbances, problems with memory and concentration (cognitive impairments), and widespread pain.
The central feature of the condition is post-exertional malaise (PEM), where all of the symptoms become worse after even low levels of physical or mental activity.
ME/CFS can affect people of any age, gender or background, though women are more likely to develop it than men.
Researchers are learning more about the biological mechanisms underpinning the disease all the time but the cause of ME/CFS is not yet fully understood.
There is currently no cure and there are no effective treatments.
Everyone who lives with ME/CFS is missing from the life they should be leading.