Which service is used for building custom AI-powered applications without machine learning expertise?

Amazon Rekognition is primarily used for image and video analysis, enabling applications to recognize objects, people, text, scenes, and activities in images and videos. While it provides powerful pre-trained models for developers to leverage, it is not a service aimed specifically at enabling users to build custom AI-powered applications without requiring expertise in machine learning.

The correct service for building custom AI-powered applications without needing deep machine learning expertise is Amazon Lex. This service allows developers to create conversational interfaces using voice and text, effectively enabling the creation of chatbots that can interact naturally with users. Amazon Lex provides a simple way to integrate natural language understanding and automatic speech recognition, allowing users to focus on application logic rather than the complexities of machine learning.

Other services listed, such as Amazon Comprehend, which is focused on natural language processing, and Amazon Machine Learning, which requires some level of understanding of machine learning concepts, further highlight that the aim of enabling easy and custom application development aligns well with Amazon Lex's capabilities.