Glossary
Sampler
Short answer
The algorithm determining the mathematical method used to remove noise.
The sampler determines how the diffusion process is run. Different samplers give results with different character from the same prompt and want different step counts.
Some reach a result quickly with few steps; others are slower but produce more detail. Some keep changing the result as steps increase.
Practical advice: pick one sampler and stay with it. Changing samplers while learning to prompt makes it impossible to tell what caused a difference.