In pictures: Sarah Palin

Sarah Palin announces her resignation as governor of Alaska in her home town of Wasilla, 3 July 2009

Alaska Governor Sarah Palin stunned observers when she announced on 3 July that she would be resigning as governor by the end of the month.

Sarah Palin accepts her nomination as the Republicans' vice-presidential candidate at the party's national convention, 3 September 2009

Mrs Palin burst onto the US political scene when Republican presidential hopeful John McCain picked her as his vice-presidential running-mate. Her big appearance - at the Republican National Convention - was well-received.

Palin supporter hold up a placard saying "Ohio for Sarah" during the election campaign,

Although she lost credibility in subsequent TV interviews, and became a favourite target for late-night satirists, Mrs Palin retained the affections of the Republican party base.

Sarah Palin holds her infant son Trig, on stage at the Republican National Convention, flanked by daughters Bristol and Willow and Bristol's then-boyfriend Levi Johnston

Mrs Palin's family, including her disabled infant son Trig, and her eldest daughter Bristol, who became pregnant at the age of 17, have been the subject of much media attention.

Sarah Palin at her vice-presidential debate with Democratic opponent Joe Biden, 2 October 2009

After her poorly-received performances in TV interviews, expectations for Mrs Palin in her televised debate with Democratic opponent Joe Biden were low. Honours came out about even, though.

John McCain and Sarah Palin on stage on election night, 4 November 2008, after conceding

Although she was a favourite of the Republican rank-and-file, Mrs Palin's unpopularity among independents and swing voters may have contributed to Mr McCain's election defeat.

Sarah Palin speaks during the Republican Governors Association conference, 13 November 2008

After losing the election, Mrs Palin remained in the spotlight, taking part in high-profile events. Observers suggested she might be positioning herself for a presidential run in 2012.

Palin supporters outside the studio where David Letterman's show is recorded, protesting against Letterman's jokes about the Palin family

When talk-show host David Letterman made an off-colour joke about her daughter, Mrs Palin - backed by her loyal supporters - demanded an apology from him.