It is not always convenient to carry a laptop.
TTerm is a simple terminal that runs on your cell phone or tablet. It is compatible with USB OTG, which enables use of the same TTL and 232 adapter cables that we have been using for years.
This app does not have all of the features of its desktop cousin yet. For example, no provisions are in place to easily change frequencies over-air, or to upload new firmware.
For basic tasks however, TTerm will absolutely get the job done.