On the Ibuildings blog there's a new post that looks at the "evils" of a crucial part of many web applications - caching.

Recently a colleague stated that in theory, caching could be considered 'evil'. Now 'evil' is a very broad term which is used a lot in the IT community, but what does it really mean when we're talking about technical solutions? I asked around, but couldn't find a clear cut definition, so I went searching...

In his search he came across a wide range of definitions, including one mentioning bad design or implying a lack of goals with a summarized meaning of "does harm to your aesthetic and engineering judgment". He applies this to caching and, because of it being a sort of counter-intuitive way to handle content (not just the pull and push), it could be considered slightly evil. Interesting interpretation...

However, as anyone will tell you caching is a very necessary evil. [...] So while it does some minor harm to aesthetic and engineering judgment, the user gets a fast experience, which is really all that matters in the end.