Seed in Stable Diffusion is a number used to initialize the generation. You don't need to come up with the number yourself because it is randomly generated when not specified. But controlling the seed can help you generate reproducible images, experiment with other parameters, or prompt variations.

The most important thing about seed is that generations with the same parameters, prompt, and seed will produce precisely the same images. Thanks to that, we can generate multiple similar variations of the picture. Let's look up some examples.

With this prompt for the  'portrait of a girl'  and the seed of 438233955, we can modify exactly the same character, changing only the facial expression changing only the text prompt modification.

'smiling'

'laughing'

'sad'

'angry'

As we see, modifying just one word that defines emotion changes her facial expression while maintaining the other visual features like hair, clothes, and background.

Similarly, we can change the look of the whole image, for example, generating a 'tree' during each of the four seasons:

'winter'

'autumn'

'summer'

'spring'

or applying different artistic style to the 'sunset' painting:

'fauvism'

'impressionism'

'oil painting'

'watercolour'

A prompt is one of many parameters you can modify to generate image variations with the same seed. See our guides for steps, guidance scale, and negative prompts for more examples.