Termux is an Open Source terminal emulator for Android that can be installed and used without rooting or complex setup. A terminal emulator is a software application that enables access to a command-line interface (CLI) in a graphical environment.

The first Termux version was released in 2014. Currently, the latest version can be installed from F-Droid Store. The installation process is simple like any other Android application.

What can we do with Termux?

The main Termux app contains a small base system that can be extended with packages that can be installed with the APT package manager.

Device Automation

With Termux Scripts and Termux Tasker, we are able to automate tasks like: send an SMS, make a call, download content, and many other tasks.

The Tasker add-on can be installed from F-Droid Store.

File transfer & synchronization

Rsync package for Termux enables the option to transfer and keep files updated across multiple devices.  Rsync is a Linux-based application also compatible with Mac and Windows. That is used to sync files between remote and local servers..

SSH Client

SSH (Secure Shell Protocol) is a cryptographic network protocol that provides a secure connection to remote hosts.  We can choose between two SHH clients, "OpenSSH" or "dropbear".

How to install OpenSSH on Termux?

To install the OpenSSH package run the  next commands:

pkg upgrade
pkg install openssh

Programming

Termux enables software development, information science education, and experimentation on mobile devices. Termux contains packages to work with  Python, C / C ++, Ruby, Golang, Rust, PHP, and other programming languages.

Source: https://wiki.termux.com/wiki/Main_Page