Mental or physical illnesses also play vital roles in the employment participation of homeless individuals or those at risk for becoming homeless. Research statistics illustrate that a disability, mental or physical, can result in difficulty acquiring work. In addition to mental illness and substance abuse, incarceration also serves as a barrier for employment. Incarceration can decrease the types of employment available to an individual after release from jail or prison. Along with the previously mentioned barriers, the lack of access to technology serves as a handicap for the homeless searching for work. In this job market, some knowledge of computers and technology is essential for every field. Although there are computers available through public access, some homeless individuals lack computer knowledge and fear failure.