The UN's World Health Organization declared the Ebola outbreak in West Africa a Public Health Emergency of International Concern (PHEIC) in the early morning of August 8.
So what does that actually mean?
Technically, it means that the WHO committee thinks the outbreak is a public health risk to other nations and that the outbreak might be in need of an international response. Those are the general criteria for the PHEIC category.
This does not, however, mean WHO will go in and fix everything in the Ebola fight. The declaration itself comes with recommended things that various nations should do, but it doesn't automatically come with funding, gloves, aid workers, or any of the other resources that the exceptionally poor nations with Ebola need to actually do those things.
Doctors Without Borders director of operations Bart Janssens summed it up well in statement: "Declaring Ebola an international public health emergency shows how seriously WHO is taking the current outbreak but statements won’t save lives. . . . Countries possessing necessary capacities must immediately dispatch available infectious disease experts and disaster relief assets to the region." Doctors Without Borders has been one of the major organizations directly treating Ebola patients.
Since WHO started using the PHEIC category in 2007, the organization has only declared it two other times: for the 2009 swine flu pandemic and for polio in May of 2014. Polio doesn't seem to have improved since that statement, according to the AP.
In the WHO's declaration about Ebola, its recommendations include that Guinea, Liberia, Nigeria, and Sierra Leone should screen for Ebola at major exit points from their countries, including airports. The WHO also says that Ebola patients shouldn't cross borders, unless for medical care, and that people who have had contact with an Ebola patient shouldn't either, until it's clear that they haven't caught the disease. That means a waiting period of 21 days, which is how long Ebola can hide in the body before it causes symptoms.
The WHO says that unaffected states don't need to institute any travel bans.
You can read the statement yourself here and listen to the related press conference here: