The document discusses concepts related to domain-driven design (DDD) including entities, value objects, services, factories, repositories, and aggregates. It provides examples of implementing these concepts in Java and Scala code and references Flickr photos that illustrate DDD concepts visually.
![Scalaに至るまでの物語 - Septeni × Scala 第一回 杉谷](https://cdn-ak-scissors.b.st-hatena.com/image/square/9e29d1ea55cbca4c5e7547ce9a4e35792d56e788/height=288;version=1;width=512/https%3A%2F%2Fcdn.slidesharecdn.com%2Fss_thumbnails%2F20150218septeniscala-150219070553-conversion-gate01-thumbnail.jpg%3Fwidth%3D640%26height%3D640%26fit%3Dbounds)