At the request of several QAs in the community, here is a test plan template you can use in your projects.
Open the template in Google Docs ↗
Always remember to check the version, because I will keep uploading updates. This first version is complete: use whatever information you need and, if an item does not apply to your project, simply remove it.
An important note: there are many ways to write a test plan, so this is not the only one. But it is the one I have used for a long time and clients have always been happy with it.
I hope you find it useful. If you have any questions about a field or how to fill something in, let me know.