The Anglican and Roman Catholic Churches, local councils and prominent Westminster figures will be the focus of the independent investigation into child sexual exploitation, inquiry chairman Justice Goddard has announced.
Announcing the first phase of the inquiry, she said they were "determined to succeed", and warned that the inquiry expected the "full cooperation" of all involved.
The said 12 areas of investigation have been identified, enabling the inquiry to identify how institutions has "failed to protect children from abuse".
Some may conclude in as soon as 18 months, she said, while others may take several years - and any criminal proceedings prompted by findings may cause further delays.
The inquiry will look at failures by local authorities, criminal justice and law enforcement, education, religion, national and private service organisations, and abuse by persons of public prominence, she said.
The first category of investigation is institution-specific, she said, with the inquiry examining specific organisations or types of organisation.
They will investigate:
Failure to protect children in the care of Lambeth Council
Failure to protect children in the care of Nottingham City and Nottinghamshire County Councils
Failure to protect children in the care of Rochdale Council
Child sexual abuse in the Anglican and Roman Catholic Churches
Medomsley Youth Detention Centre
How custodial institutions in general failed to protect children from sexual abuse
Sexual abuse in residential schools
The second category of the inquiry will look at broader areas of concern, she added, where multiple institutions should protect children from abuse.
This will include:
Sexual abuse facilitated by the internet
Sexual exploitation of children by organised networks
Extent to which institutions in England and Wales are effectively discharging their responsibilities in protecting children abroad
Adequacy of existing services for providing support to victims and survivors
They will also conduct an overarching investigation into allegations of child sexual abuse by certain people of "public prominence associated with Westminster", she added.
Children living in care or with foster carers were among the "most vulnerable in society", she said, and victims deserved a thorough examination of what may have happened.
A "wide spectrum" of public authorities in Lambeth and Nottinghamshire failed to protect children, she added.
In Rochdale, the inquiry will look at children in residential accommodation, including allegations that boys who attended Cambridge House Boys Hostel or Knowl View School were subject to sexual abuse by specific individuals, including former Liberal Party MP Cyril Smith.
Allegations of child abuse within the Anglican and Roman Catholic Churches will be examined, along with abuse within other faith communities - and Justice Goddard promised these would lead to "other investigations" in time.
"The sexual abuse of children in the Roman Catholic Church has been a matter of national and international concern for many years," she said.
The English Benedictine Congregation of Catholic monks and nuns will be included.
In the Anglican church, the Diocese of Chichester - which has been "beset" with allegations of abuse - will come under particular scrutiny, along with the case of former Bishop of Lewis and Bishop of Gloucester Peter Ball, and whether there were "inappropriate" attempts by leaders to interfere with the criminal justice system when allegations were made against him.
There were "hundreds" of allegations of abuse relating to Medomsley Youth Detention Centre in County Durham, she added, and the inquiry would look into how - if true - the offending went undetected for so long.
Meanwhile, she said, the impact of the internet on child exploitation was an "urgent matter of contemporary importance".
The abuse of children by organised networks will be another aspect of the inquiry, looking at the "systematic grooming and sexual abuse of children" by people in cities and towns across England and Wales - which she said was "widespread".
And an "objective fact-finding inquiry" will be carried out into high-profile allegations of abuse by "people of public prominence associated with Westminster", including current or former MPs, senior civil servants, government advisers and members of the security and intelligence agencies.
Further allegations of cover-up and conspiracy will be among the items looked at.