Tertius was one of Paul's scribes, who helped him write his words down. Tertius the software package is two things: it's a Javascript library for helping people to create rich client-side Bible study tools; it's also a sample study tool created using the Tertius library.

End users can use Tertius as a web-based application or as a mobile application. The mobile application is much faster and more efficient, but the web app should work everywhere.

You can try out Tertius at http://simoncozens.github.io/tertius/

The idea behind Tertius is that you can use as little or as much of the library as you need to put together the kind of applications that you want. You may only want the code which provides access to Bible data; that's fine, go ahead. You may just want the code which co-ordinates searching and retrieving and substitute in your own data backend; again, no problem. You might even just want the reference parser and the book information file. It's up to you. Tertius is provided under the BSD 3-clause licence (see LICENCE.md) so you're free to modify it, build on it or make commercial applications out of it although I would strongly encourage you not to call those applications "Tertius", reserving that for the reference implementation.

See IMPLEMENTATION.md and the various source code files to make sense of what it does and why.