> For the complete documentation index, see [llms.txt](https://targets.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://targets.gitbook.io/docs/introduction/what_is_a_spec.md).

# What is a "spec"?

Targets can be written as code, or, for certain types of targets—such as shell commands or HTTP requests—targets can be declared. When declaring a target, we call this a "spec". Targets supports a few useful spec formats out-of-the-box, and supports custom loaders which enable you to implement your own spec interpreters.