Machine learning is the branch of artificial intelligence where a computer learns to make predictions from examples rather than following rules a human wrote out.
The distinction is worth making concrete. In traditional programming, a developer writes the logic: if the transaction is above Rs 50,000 and from a new device and outside the usual city, flag it. In machine learning, you instead show the system a few million past transactions labelled fraudulent or genuine, and it works out the patterns itself, including patterns no analyst would have thought to write down.
The three main styles
Supervised learning uses labelled examples. Each training case comes with the right answer, and the model learns to map inputs to outputs. This covers most practical business use: predicting loan default from applicant history, classifying an email as spam, estimating a house price from its features, reading the amount on a cheque.
Unsupervised learning has no labels. The model finds structure on its own, typically by grouping similar things together. A bank might use it to discover natural customer segments it had not defined in advance, or to spot transactions that look unlike anything else and therefore deserve a look.
Reinforcement learning learns by trial and feedback. The system takes actions, receives a reward or penalty, and adjusts. This is how systems learn to play games, route delivery fleets, or manage warehouse robots.
How training actually works
Take a model predicting whether a loan applicant will default.
- Gather data. Thousands of past applicants with their income, existing obligations, credit history, employment type, and crucially whether they actually defaulted.
- Split it. Most of the data trains the model. A held-back portion tests it on cases it has never seen.
- Train. The model makes predictions, compares them with the true outcomes, and adjusts its internal parameters to reduce the error. It repeats this many times.
- Test. Accuracy is measured on the held-back data. Only this number means anything.
- Deploy and monitor. Real-world performance drifts as behaviour changes, so models are retrained periodically.
Overfitting, in one image
A model that memorises the training data rather than learning the underlying pattern is overfitted. It scores brilliantly on data it has seen and poorly on anything new.
The everyday analogy: a student who memorises the answers to last year's paper and is lost when the questions change. This is why the held-back test set exists, and why any claim of very high accuracy should be met with the question "on data the model had never seen?"
Garbage in, garbage out
A machine learning model can only learn what its data contains, including the data's mistakes.
If a lender's historical decisions were biased against applicants from certain areas, a model trained on those decisions learns to reproduce that bias, and it does so with an air of mathematical objectivity that makes it harder to challenge. If the training data covers only metro customers, performance on rural applicants will be worse without anyone noticing.
For Indian applications specifically, models trained mostly on Western data often handle Indian names, addresses, transliteration, regional languages and local income patterns poorly. This is a data problem, not a technology problem, and it is fixed with better local data rather than a bigger model.
Where you meet it in India
- Credit scoring at banks and NBFCs, increasingly using alternative data alongside bureau scores
- UPI and card fraud detection, which must decide in milliseconds
- Insurance claim triage and premium pricing
- Crop yield and price prediction in agri-tech
- Demand forecasting for quick commerce and logistics
- Speech recognition across Indian languages
- Recommendations on every content and shopping app you use
Practical implications if you are using AI tools
Machine learning is the engine underneath large language models, which are trained on enormous text datasets using neural networks. That inheritance explains their behaviour:
- They generalise from patterns, so they can be confidently wrong on anything underrepresented in training data.
- They have a training cutoff. A model does not know a rule changed in the last Budget unless it can search.
- They reflect their data's skew, which is why output about Indian contexts is sometimes noticeably weaker than about American ones.
- Accuracy claims need context. "95% accurate" is meaningless without knowing on what data and against what baseline.
If you are evaluating an AI product for a business, the questions that matter are what data it was trained on, how it performs on cases like yours, and what happens when it is wrong.