The IndexError: list index out of range error occurs in Python when an item from a list is attempted to be accessed that is outside the index range of the list. The range of a list in Python is , where n is the number of elements in the list.
User engagement means how much a person uses an app and stays interested in it. It's super important for developers to give users good reasons to keep using their app. In mobile marketing, a big goal is to get more people engaged with apps. This can be done in different ways like sending them emails that they're interested in, making content that's just for them, and trying out new marketing ideas.
In this series, we have looked at the "musts" (databases) and "shoulds" (asynchronous jobs, websockets) of a web application. Now we turn to one of the "coulds" (that is nonetheless recommended for scaling businesses): caching. In particular, we mean caching HTML fragments and other snippets of data, as referred to in Rails Guides. We are not concerned with HTTP or SQL query caching. In this part, we'll see how to speed up our Rails app using LiteCache.