Tendermint Core is Byzantine Fault Tolerant (BFT) middleware that takes a state transition machine - written in any programming language - and securely replicates it on many machines. In other words, a blockchain.
Tendermint requires an application running over the Application Blockchain Interface (ABCI) - and comes packaged with an example application to do so. Follow the [installation instructions](./install) to get up and running quickly. For more details on [using tendermint](./using-tendermint) see that and the following sections.
Testnets can be setup manually on one or more machines, or automatically on one or more machine, using a variety of methods described in the [deploy testnets section](./deploy-testnets). For more information (and to join) about the Cosmos Network testnets, see [here](link).
## Application Development
The first step to building application on Tendermint is to [install ABCI-CLI](./getting-started) and play with the example applications.
