A missing person is a person who has disappeared for usually unknown reasons.

Missing persons' photographs may be posted on bulletin boards, milk cartons, postcards, and websites, along with a phone number to be contacted if a sighting has been made.

People disappear for many reasons. Some individuals choose to disappear alone; most of these soon return. Reasons for non-identification may include:

• To escape child abuse, such as child physical abuse, emotional abuse, by a parent(s) / guardian(s) / sibling(s) (especially).
• Leaving home to live somewhere else under a new identity.
• Becoming the victim of kidnapping
  Kidnapping
  In criminal law, kidnapping is the taking away or transportation of a person against that person's will, usually to hold the person in false imprisonment, a confinement without legal authority...
  
  .
• Abduction
  Child abduction
  Child abduction or Child theft is the unauthorized removal of a minor from the custody of the child's natural or legally appointed guardians....
  
   (of a minor) by a non-custodial parent or other relative.
• Seizure by government officials without due process of law
  Due process
  Due process is the legal code that the state must venerate all of the legal rights that are owed to a person under the principle. Due process balances the power of the state law of the land and thus protects individual persons from it...
  
  .
• Suicide
  Suicide
  Suicide is the act of intentionally causing one's own death. Suicide is often committed out of despair or attributed to some underlying mental disorder, such as depression, bipolar disorder, schizophrenia, alcoholism, or drug abuse...
  
   in a remote location or under an assumed name
  Pseudonym
  A pseudonym is a name that a person assumes for a particular purpose and that differs from his or her original orthonym...
  
   (to spare their families the suicide at home, or to allow their deaths to be eventually declared in absentia
  Death in absentia
  Death in absentia is a legal declaration that a person is deceased in the absence of remains attributable to that person...
  
  ).
• Victim of murder
  Murder
  Murder is the unlawful killing, with malice aforethought, of another human being, and generally this state of mind distinguishes murder from other forms of unlawful homicide...
  
   (body disguised, destroyed, or hidden).
• Mental illness or other ailments such as Alzheimer's Disease
  Alzheimer's disease
  Alzheimer's disease also known in medical literature as Alzheimer disease is the most common form of dementia. There is no cure for the disease, which worsens as it progresses, and eventually leads to death...
  
   can cause someone to become lost, or they may not know how to identify themselves due to long term memory loss that causes them to forget where they live, the identity of family members or relatives or even their own names.
• Death by natural causes (disease) or accident far from home without identification.
• Disappearance in order to take advantage of better employment or living conditions elsewhere.
• Sold into slavery, serfdom, sexual servitude, or other unfree labour
  Unfree labour
  Unfree labour includes all forms of slavery as well as all other related institutions .-Payment for unfree labour:If payment occurs, it may be in one or more of the following forms:...
  
  .
• To avoid discovery of a crime or apprehension by law-enforcement authorities.