DALL-E 2 is the successor to DALL-E (formerly DALL-E Mini) and brings with it a big improvement to generated image quality. Perhaps still not up to the quality of Stable Diffusion and Midjourney, but depending on your prompts you can get some fantastic images.
The model was trained on a dataset of text-image pairs, where the text provides a description of the visual content of an image. When given a new text description, DALL-E 2 uses the relationships and patterns it learned from the training data to generate a corresponding image.
Compared to the original DALL-E, the produced images are both more realistic and boast 4x the resolution. The trade-off is the payment model; since DALL-E 2 now requires users to purchase credits in order to continually use the service. You can however try DALL-E 2 for free before purchasing any credits. Upon creating an account with OpenAI you will be allotted 50 free credits, and 15 credits each month afterwards. Each generated image with DALL-E 2 costs 1 credit.