📉 Why We Split Data

If you train and evaluate a model using the exact same dataset, you're only testing how well it remembers.

That's why datasets are usually split into:
👉 Training set → The model learns from this.
👉 Validation set → Used to tune model settings.
👉 Test set → Used only once at the end to measure real performance.

Think of it like studying for an exam.
Reading the textbook is training. Practice questions are validation. The final exam is the test set.