The players need to interact with the NPCs. Most often players need to ask the NPCs something or chat with them to share information. There are several types of conversation system. Each one comes with its pros and cons.
It is important to choose a right conversation system for the virtual world.
Text parsing conversation is a prompt box with a text input box for a player to input the sentence they want to say. After which, the NPC will parse the sentence and respond to the player with related information. It is similar to talking with a chat bot.
Text parsing interaction existed for a long time as old text game without graphic user interface. At that time, the computer was not fast ...