What is swine flu?
Swine flu is a respiratory disease, which means it's to do with breathing, that usually affects pigs.
It's is caused by a strain of the influenza virus and is a bit like human flu, in that there are loads of different types and the infection is constantly changing.
The disease regularly breaks out among herds of pigs, but although it can make the animals very ill they normally survive.
Can humans catch swine flu?
Herds of pigs are regularly hit by swine flu, but usually survive
Swine flu doesn't usually affect humans and in the past, those who have had it have normally been in close contact with pigs.
But officials say this latest outbreak IS being passed from person to person and it's thought to be passed on in the same way as human flu... by coughing and sneezing.
So what's changed?
Some swine flu cases are a new type of H1N1 strain of the influenza virus
Experts at the World Health Organisation say at least some of the cases are a new version of the H1N1 strain of the influenza type A virus.
Doctors who have studied the bug have found that it's like other types of flu, but has bits mixed into it from the flu bugs that pigs and birds can catch.
How dangerous is it?
Symptoms of swine flu in people appear to be similar to those of human flu, including having a fever, cough, body aches or chills etc.
Cases of swine flu have been confirmed in several different countries.
Many cases that have been reported so far appear to be mild, but hundreds of people have been killed around the world, including in the UK.
Some medical experts think the number of people who die in the UK from swine flu could rise much higher.
However, between 6,000 and 8,000 people die from ordinary flu and related illnesses in the UK every year.
Some people who catch the swine flu bug may not even realise they have it.
What's being done to keep us safe?
Governments around the world are doing all they can to stop swine flu spreading and say they have plans in place to deal with the outbreak.
In Taiwan, a pig farm is disinfected to try to prevent an outbreak of swine flu
Officials in America say two types of medicine that are usually used to treat flu have also worked well for swine flu patients there, if they've been given it early enough.
The British government has got millions of doses of the flu medicine ready if someone in the UK catches the disease.
Meanwhile, scientists are also working on a medicine specifically designed to treat this latest strain of swine flu.
Is it safe to eat bacon sarnies and other pig meat?
Yes. Officials say there's no evidence you can catch swine flu by eating meat from infected animals, but it's important to make sure it's cooked properly.