The effects of API design will likely live with your project for a long time, often beyond your tenure with the project. Yet good API design is very rarely discussed and often leads developers to the conclusion that good APIs are something that "we know when we see them."

This talk will attempt to layout a set of fundamentals for good API design so that we can begin to really understand the difference between well-designed APIs and those that are mediocre. It will also explain about various trade-offs that are made when designing APIs and some of the pros and cons that come with each trade-off. Finally we'll take a look at some good APIs and bad APIs in Ruby.