Ebola - or Ebola haemorrhagic fever (EHF) - is a really deadly virus: 50% to 90% of people who catch it die.
But there are a few forms of the virus which have been identified by scientists.
But if you get the right medical care and treatment, you can recover.
Where has it come from?
Ebola was first spotted in the African countries of Sudan and the Democratic Republic of the Congo in 1976.
In five months 284 people in Sudan caught the virus.
It killed 117.
How do you get it?
You can catch it through direct contact with the body fluids of an infected person such as blood and saliva.
It is not airborne like the flu so is more difficult to catch but is very infectious: so infected people have to be kept separate to reduce the risk of it spreading.
Health care workers who have looked after sick patients have also been infected.
What's it got to do with animals?
It's thought Ebola is carried by animals too - chimpanzees and monkeys have been badly affected by the virus.
It is spread to humans from close contact with infected animals and can then be passed between people.
This latest outbreak has been linked with fruit bats - which are considered a tasty meal in parts of Africa.
Is there a cure?
There is no cure or vaccine for Ebola but a new experimental drug, ZMapp, has been used in the US on health workers and a UK nurse who caught the disease in Africa. They recovered from the virus.
You lose a lot of fluids when you have the disease so giving people enough water and the right vitamins, minerals and nutritious food is one of the main treatments.
October - The government announced that more is being done to deal with the risk of the Ebola virus in the UK.
People will be able to ring a special phone line and will be asked questions about their travel history and possible symptoms.
Experts will be on standby with several hospitals ready to deal with any possible cases.
The Ebola virus has spread across West Africa in recent months and prompted lots of questions from you.
We asked virus expert Dr Benjamin Neuman to answer some of your questions.
20th October - Nigeria was declared free from Ebola after more than six weeks without any new cases.
But the World Health Organisation says Liberia, Guinea and Sierra Leone are still trying to prevent it spreading.
Lots of countries and charities are trying to help stop the outbreak of the virus by sending troops, supplies and helping to build more facilities to treat people.
Chris Worrall from the charity Oxfam, has told Martin about the work they're doing to raise awareness of the virus.
3rd September - The first British person to catch Ebola during the outbreak in West Africa made a full recovery.
William Pooley was brought back to the UK from Africa and was treated in a special isolation unit at the Royal Free Hospital in London but has now been discharged.
William was given the experimental drug ZMapp and has praised the "world class" care he received.
He was working as a volunteer nurse in one of the worst affected countries, Sierra Leone, when he caught the virus.
August - The deadly virus Ebola had killed more than 1,500 people, aid workers travel to west Africa to help.
In the fight to try to stop the disease spreading, doctors and medical staff from the UK and other countries are helping to treat those infected in Sierra Leone, Liberia, Guinea and Nigeria.
So why do so many doctors, nurses and medical staff risk their lives in dangerous places?
Dr Nathalie MacDermott, who's worked with Ebola sufferers, told Newsround what it's like to work in such a difficult environment.
Dr Tim O'Dempsey told Newsround what it's like to work in such a difficult environment.
Monday 25th August - A British man who caught Ebola when working as a nurse in Sierra Leone was treated for the virus.
The man, named as William Pooley, has been flown home to the UK and is being treated in an isolation unit at a hospital in London.
Ebola is a very serious disease and lots of people in West Africa have been affected recently.
Health experts say people in the UK should not be worried as it's extremely unlikely it will reach this country.
22nd August - Two American aid workers recover from Ebola after being treated with an experimental drug ZMapp.
Two American aid workers who fell ill with Ebola have left hospital after recovering.
Dr Kent Brantly and Nancy Writebol were working in Liberia in Africa, when they caught the disease.
They were both flown to the US for treatment three weeks ago, where they were kept in isolation in an Atlanta hospital.
Doctors who treated them say they no longer show any signs of the disease and pose no threat to the public.
Whilst in hospital, they were both given an experimental treatment known as ZMapp.
The drug, which has only been made in limited quantities, had never been tested on humans before and it's unclear whether this helped in their recovery.
7th August - World leaders met to discuss how to tackle Ebola outbreak.
In Africa, doctors are fighting to stop an outbreak of a virus that has been spreading there.
It's called Ebola and health experts from across the world are meeting to try to work out how to tackle it.
The outbreak began in December 2013, over 3,500 miles away in Guinea, and has spread to other countries in west Africa.
Health officials are working hard to get the situation under control in Liberia, Sierra Leone and Nigeria.