What is an AI Training Pipeline?

Each stage feeds the next: raw data gets ingested and deduplicated, then cleaned and normalized, then labeled or annotated (by humans, heuristics, or another model), then split into train/validation/test sets. The actual training run adjusts model weights against the training set while validation data catches overfitting early, and held-out test data gives an honest final read on quality. Modern pipelines are rarely a single training pass — they include pretraining on broad data, fine-tuning on task-specific data, and often reinforcement learning from human or AI feedback to shape behavior and tone. Each of these stages needs its own evaluation harness, because a model that scores well on one benchmark can still fail badly on the specific behaviors a product actually needs. Because pipelines are reused across many training runs, engineering discipline matters: versioned datasets, reproducible training configs, and automated evaluation gates before a new model checkpoint is allowed to replace the one currently in production. Skipping these steps is how silent regressions slip into a live system.