U.S. presidential candidates are nominated based on a complex system of primaries, caucuses and delegates. How the presidential nominating system works and the delegate math for this year's candidates.

The Obama administration presents a plan to Congress for closing the Guantanamo detention center: The timeline, where the existing detainees would be transferred and the challenges of getting support for the proposal.

Hazel and Augustus, the main characters in the young adult novel “The Fault In Our Stars,” are not your average teens: They both have cancer. For this month’s Readers’ Review guest host Katty Kay discusses the best seller “The Fault In Our Stars” with our panel of experts.

On Tuesday, primary elections were held in five states, in addition to runoffs in Mississippi and South Carolina. Katty Kay guest hosts as our panel analyzes the results and what they mean for the Tea Party and the makeup of the next Congress.

Research shows that women are less confident than men and D-N-A is partly responsible. But two journalists argue that biology is not destiny. What we can learn from successful women who take risks and are not afraid of failure.

Rival protesters clash in Ukraine's Crimea region. Ongoing political violence in Venezuela leads to more than 50 deaths. And President Barack Obama warns Afghan President Hamid Karzai time is running out to finalize terms of a U.S. troop withdrawal. A panel of journalists joins guest host Katty Kay for analysis of the week's top international news stories.

A new Pentagon budget scales back the Army to pre-World War II levels. Arizona Gov. Jan Brewer vetoes a controversial anti-gay bill. And Rep. John Dingell, the longest-serving member of Congress, announces his retirement. A panel of journalists join guest host Katty Kay to discuss the week in news.

Geneva talks on Syria stall as negotiators fail to agree on conditions. Deposed Egyptian President Mohamed Morsi goes on trial. And the European Central Bank cuts its benchmark interest rate to a record low. Guest host Katty Kay and a panel of journalists discuss the week's top international stories.

Health and Human Services Secretary Kathleen Sebelius rejects calls to delay parts of the Affordable Care Act. The Senate votes on a bill to ban workplace discrimination based on sexual orientation. And the U.S. economy grew at a faster-than-expected pace in the third quarter. Guest host Katty Kay and a panel of journalists discuss the week's top national stories.

The author of "The Selfish Gene" and "The God Delusion" talks about the evolution of his own thinking.

Shootings and a hostage crisis in Nairobi underscore the resilience of al-Qaida and its affiliates in Africa. Guest host Katty Kay and her guests discuss international terrorism and implications for security at home.

The brutal killing of a British soldier in London raises terror alarms. Secretary of State John Kerry meets with Israelis and Palestinians. And the White House acknowledges drone strikes have killed four Americans overseas since 2009. A panel of journalists joins guest host Katty Kay for analysis of the week's top international news stories.

Analysis of President Barack Obama’s national security speech. Response to tornado damage in Oklahoma. And an official at the Internal Revenue Service invokes her Fifth Amendment right in a House investigation. A panel of journalists joins guest host Katty Kay for analysis of the week's top national news stories.

Iran's supreme leader rejects direct talks with the U.S. Turmoil in Tunisia following the assassination of an opposition leader. And the remains of England's Richard III are found and identified. A panel of journalists joins Diane for analysis of the week's top international news stories.

The White House agrees to give Congress classified drone documents. The Justice Department sues Standard and Poor’s. And the Post Office announces plans to end Saturday delivery. A panel of journalists joins Diane for analysis of the week's top national news stories.

A journalist exposes the failures of an entire community to protect the 3-year-old daughter of a close family friend.