从一篇文章中提取特定主题的句子。
请提取这篇关于人工智能的文章中涉及“机器学习”的句子。
以下是提取的句子：

- "Machine learning is a subset of artificial intelligence that involves giving a computer system the ability to automatically learn and improve from experience without being explicitly programmed."
- "With machine learning, the computer is able to automatically identify patterns and learn from them, allowing it to make accurate predictions or decisions without the need for human intervention."
- "There are three main types of machine learning: supervised learning, unsupervised learning and reinforcement learning."
- "Supervised learning involves feeding the computer system with data that has already been labeled or classified, allowing it to make predictions or decisions based on the patterns it recognizes in the data."
- "Unsupervised learning, on the other hand, involves allowing the computer system to analyze unlabeled data and identify patterns and relationships without any specific guidance."
- "Reinforcement learning is a type of machine learning that involves training a computer system with a reward-based system, with the goal of teaching it to make decisions that will maximize the reward over time."