SillyTavern is a user interface you can install on your computer (and Android phones) that allows you to interact with LLMs backends and APIs.
SillyTavern is developed by Cohee and RossAscends
Modern AI language models have gotten so powerful that some of them are now convincingly able to simulate a character you create, and who you can chat with. For example, you can tell the AI to act as an expert code reviewer to help you code or a novel editor to help you edit your book. You can assign personalities and actions to the LLM and it will persist through the interaction.