As we have seen the different types of clients, let's see what kinds of data they produce.

In today's world, data can be categorized into three types:

• Structured data: Structured data is well defined data and the entire dataset follows a schema for such data. Examples of structured data are CSV files and RDBMS databases.
• Unstructured data: Unstructured data, on the other hand, is not well defined and there are structural changes to the data throughout the dataset. Examples of unstructured data are audio files, video files, and image files.
• Semi-structured data: Data that is present in emails, log files, text files, or word documents is considered unstructured data.

So, data has three types, and we need a cognitive service that can consume this data and respond with an intelligent response. So, let's define what a cognitive service is.