What is Backpropagation?Backpropagation kya hai?

🧸 Think of it likeAise samjho

Like a cricket coach watching a lost match on replay and working out how much each player's mistake cost, so each one knows what to fix.Jaise cricket coach haare hue match ka replay dekh kar pata karta hai ki har player ki galti ka kitna asar hua, taaki har koi jaane kya sudhaarna hai.

📘 ExplainedVistaar se

After a forward pass produces a prediction and a loss, backpropagation applies the chain rule from the output back to the first layer, computing the gradient of the loss for every weight. An optimiser like SGD or Adam then nudges the weights. Frameworks such as PyTorch do this automatically (autograd).Forward pass se prediction aur loss milne ke baad, backpropagation output se pehli layer tak chain rule lagata hai aur har weight ke liye loss ka gradient nikaalta hai. Phir SGD ya Adam jaisa optimiser weights ko thoda khiskaata hai. PyTorch jaise frameworks yeh apne aap karte hain (autograd).

💡 Real exampleAsli example

Like a teacher tracing which step in a long sum caused the wrong answer.Jaise teacher dhoondhe ki lambe sawaal ka kaunsa step galat jawaab ki wajah bana.

📖 Learn it step by stepStep by step seekho

• Gradients and gradient descent: how models improveGradients aur gradient descent: models behtar kaise hote hain
• Neural networks: layers that learnNeural networks: layers jo seekhti hain

🔗 Related termsJude hue shabd

• GradientThe direction and steepness in which the error grows; models step the opposite way to improve.Woh direction aur dhalaan jisme error badhta hai; models sudharne ke liye ulti taraf kadam lete hain.
• Gradient descentThe training method that repeatedly adjusts weights in small steps to reduce error.Training ka tarika jo error kam karne ke liye weights ko baar baar chhote kadmon mein badalta hai.
• Loss functionA formula that measures how wrong the model's predictions are; training tries to make it small.Formula jo naapta hai model ki predictions kitni galat hain; training ise chhota karne ki koshish karti hai.