Gradient descent is an iterative optimization algorithm used to minimize a function. In machine learning, this function typically represents a loss function that we aim to reduce in order to improve our model's performance. The gradient of a function at a specific point indicates the direction of the steepest ascent, while its magnitude reflects the slope's steepness at that point. Gradient descent utilizes this principle by continuously adjusting the parameters of our function to progress toward the direction of steepest descent, thus minimizing the function. Standard gradient descent updates parameters using the entire dataset, which can be resource-intensive, especially with large datasets. To mitigate this issue, adaptations like Stochastic Gradient Descent (SGD) and Mini-batch Gradient Descent were developed. SGD updates parameters for each individual training example, whereas Mini-batch Gradient Descent updates parameters after processing a group of examples. This approach is crucial in machine learning and deep learning, as it enables the optimal tuning of model parameters across a range of tasks.