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---
description: Explore the detailed information on key Ultralytics callbacks such as on_pretrain_routine_end, on_model_save, on_train_start, and on_predict_start.
keywords: Ultralytics, callbacks, on_pretrain_routine_end, on_model_save, on_train_start, on_predict_start, hub, training
---
## on_pretrain_routine_end
---
### ::: ultralytics.utils.callbacks.hub.on_pretrain_routine_end
< br > < br >
## on_fit_epoch_end
---
### ::: ultralytics.utils.callbacks.hub.on_fit_epoch_end
< br > < br >
## on_model_save
---
### ::: ultralytics.utils.callbacks.hub.on_model_save
< br > < br >
## on_train_end
---
### ::: ultralytics.utils.callbacks.hub.on_train_end
< br > < br >
## on_train_start
---
### ::: ultralytics.utils.callbacks.hub.on_train_start
< br > < br >
## on_val_start
---
### ::: ultralytics.utils.callbacks.hub.on_val_start
< br > < br >
## on_predict_start
---
### ::: ultralytics.utils.callbacks.hub.on_predict_start
< br > < br >
## on_export_start
---
### ::: ultralytics.utils.callbacks.hub.on_export_start
< br > < br >
