KISS, "Keep It Simple Stupid" (or the less pejorative "Keep It Short and Simple") is a principle that suggests favoring simplicity over complexity. Simple code is easier to read and consume.
There are many code smells that deal with detecting complexity and refactoring it to simpler code. These smells deal with specific areas of complexity such as class-level complexities, method-level complexities, and so on. Simplicity can apply in many other places.
Computer language syntax has a subset that deals with a more general context and sometimes a subset that deals with more specific contexts. C# is no exception. There have been additions to the language for specific scenarios. Lambdas, for example, are a means towards functional programming that promote side-effect-free programming and avoid having to specify the details of the algorithm. Lambdas are a key part of the LINQ story. While you can use LINQ without lambdas, it's hard to avoid lambdas with complex LINQ statements.
Lambdas...