Any software developer should be used to having to learn new libraries or languages, but for me, it’s been a bit extreme. I stopped coding in 1988 when I went into technical management, and I didn’t come back to coding until 2009—that’s a 21-year gap. To say that the landscape had changed is an understatement; I felt like a child on Christmas morning with so many lovely presents I couldn’t take it all in. I made all the rookie mistakes at the beginning, like thinking object-oriented programming was about using inheritance, which it isn’t. But I learned the new syntax, new tools (wow!), and reveled in the amount of information I could get online. I chose to focus on Microsoft’s stack, mainly because of the wealth of documentation available. That was a good choice at the time, but now with .NET Core and its open source, multiplatform approach, it turns out to be an excellent choice. The first applications I worked on in 2009 were ones that optimized and displayed healthcare needs geographically, especially around where to locate treatment centers. That required complex math (which my wife provided) and serious database work. I went through ADO.NET, LINQ to SQL, and then in 2013 I swapped to Entity Framework (EF), when EF 5 supported SQL’s spatial (geographical) types. Over the intervening years, I used EF a lot and have come to know EF6.x well. I’ve written extensively on EF in my own blog (www.thereformedprogrammer.net/) and on the Simple Talk site (www.simple-talk.com/author/jon-smith/). It turns out I like taking complex software ideas and trying to make them easy for other people to understand. So, when Manning Publications approached me to write a book on Entity Framework Core (EF Core), I said yes.