 Hi to everybody! My name is Raffaela Gozzellino and I'm the Director of the Atlantic Technical University, located in San Vicente Island in Cape Verde. I'm also professor at Nova Medical School, Nova University of Lisbon and a group leader of a research lab in the Chronic Diseases Research Center. Today I would like to explain to you what the DOI stands for and what it means. DOI stands for Digital Object Identifier and is a way to assign a unique identifier to a series of items that can vary from journal articles, books, conference proceedings, scientific and governmental reports, data sets, etc. It is usually as well assigned to other type of works, like for instance codes or like commercial videos. In case of journals articles, the digital object identifier appears as soon as you look for the article near the publication date. It's a string of alphanumeric numbers that starts with 10 and it includes a prefix and a suffix separated by a slash. The prefix is a more permanent digit of four or more numbers and it is assigned to organization. This is why it's permanent. However, the suffix is assigned by publishers and it is influenced therefore by international publisher standards. The digital object identifier is very important for academic citation because it's more stable than URLs. Indeed, we can find research articles or articles in general of course but we can find them associated to the different URLs that then can be changed or removed over time. However, if all these items have a digital object identifier, this is permanent and the reader can always find the location source. If he clicks on it or it pasted into the browsers, always can find what it looks for. So it's something that accompanies the life of the entire document and it never changed. The digital object identifier system have been implemented by the International Digital Object Identifier Foundation through the many registration agency that are located in different geographical areas and Crossref is one of those agencies which attributes digital object identifier numbers to scholarly research articles. There is something however that you should know as well that not all articles or not all items I mentioned before are associated with the digital object identifier because publications in order to have a stable link that identify those papers needs to pay a fee. So I really hope that now it is more clear what the DOI stands for and what it means. So look it into your browser.