This book entitled Covid - 19 Diary of a Pandemic 2020-2023 consists of 42 chapters, five of which have the structure of a diary and the others are essays, reflections and compilation of figures. I started writing it in 2020 and the last notes were incorporated in November 2023.I always felt that I had a diary to write. I did not do it during my youth, nor at another stage of my life; but the special context of a pandemic such as the coronavirus disease motivated me enough, being a doctor by profession, to start recording information, which was really a lot, in the midst of the great advances in medicine, computing, informatics, internet, social networks, cellular telephony and more recently artificial intelligence.