The woman, from Burton upon Trent in central England who cannot be named for legal reasons, was arrested by counter-terrorism officers at London's Heathrow Airport in February after arriving on a flight from Turkey.
Read: IS recruitment: British, US med students head to Turkey
West Midlands Police said she had been charged with publishing messages on Twitter in October last year which encouraged people to commit or prepare acts of terrorism, and being a member of the banned organisation Islamic State (IS).
BREAKING: A Burton woman has been charged with inciting terrorism on social media and being a member of the proscribed terrorist group ISIS.
— West Midlands Police (@WMPolice) July 2, 2015
The woman was arrested by officers from the West Midlands Counter Terrorism Unit at Heathrow Airport in Feb. More: http://t.co/rIYjwXg6qi
— West Midlands Police (@WMPolice) July 2, 2015
She is due to appear before magistrates in London later on Thursday.
About 700 Britons are estimated by the authorities to have travelled to Syria or Iraq, many to join Islamic State, and on Wednesday police said they feared a family of 12 had been the latest to make the journey.
Britain has stepped up attempts to try to stop people going or arrest them on their return, while Prime Minister David Cameron has called on social media firms to do more to deal with online extremism, saying some young Britons had been radicalised "in their bedrooms".
Read: Islamic State seen as potent force a year after caliphate declaration Pentagon
"(IS's) methods of murder may be barbaric, but its methods of recruitment, propaganda and communication use the latest technology," he told parliament this week.
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