Kaggle is a platform for data science competitions where participants can learn from experts, work with interesting real-world datasets, and potentially win prizes. Competitions involve building predictive models on a training dataset, submitting predictions for a test dataset, and being scored based on accuracy. Competitors can use any open-source language and should focus on feature engineering, trying different algorithms and models, and building ensembles of multiple models to improve performance. Participating is a way to learn and improve skills in machine learning and data science.