Operation World is a long-running project to encourage prayer for all peoples and nations around the globe. It used to exist in book form and I think I still have an edition from the late 90s. It was invaluable for looking up details of a country and gave both general demographics and things of interest to Christians, like the relative balance of different faiths and if the country saw active persecution of Christian believers.
There is also now a website and, at some point in the past, I installed their app on my iPad. However, it was only part way through last year that I started making it part of my daily routine and spending a little time praying for the country highlighted. I hadn’t realised that they started the year by praying for wider regions, like Europe or Africa, and it was only yesterday that they got back to individual countries. That is why I am declaring today that A is for Afghanistan, with over 40M souls, a high level of persecution of Christians and oppression of women, and the focus of Operation World yesterday and today.