1. What is unsupervised learning?
Unsupervised learning is a type of machine learning where the algorithm learns patterns and structures from input data without explicit labels or guidance. It aims to discover underlying patterns, group similar data points, or identify hidden relationships within the data.

2. What are the main goals of unsupervised learning?
The main goals of unsupervised learning include clustering, dimensionality reduction, and anomaly detection. Clustering involves grouping similar data points together, dimensionality reduction aims to reduce the number of input variables while preserving important information, and anomaly detection identifies unusual or abnormal instances in the data.

3. What are the common algorithms used in unsupervised learning?
Common algorithms used in unsupervised learning include k-means clustering, hierarchical clustering, Gaussian mixture models, principal component analysis (PCA), and t-SNE (t-distributed stochastic neighbor embedding). These algorithms help uncover patterns and structures in the data without relying on labeled examples.

4. How does unsupervised learning differ from supervised learning?
In unsupervised learning, the algorithm learns from unlabeled data and aims to find patterns and relationships without explicit target labels. In contrast, supervised learning uses labeled data to train models to predict or classify new, unseen examples based on the provided labels.

5. What are the applications of unsupervised learning?
Unsupervised learning finds applications in various fields, including customer segmentation, anomaly detection in cybersecurity, market basket analysis, recommendation systems, image and text clustering, and exploratory data analysis.

6. How is evaluation performed in unsupervised learning?
Evaluation in unsupervised learning can be challenging since there are no ground truth labels. Common evaluation techniques include measuring clustering quality using metrics such as silhouette score or elbow method, assessing dimensionality reduction performance by preserving data variance, and validating anomaly detection results through expert analysis or labeled datasets.

7. What are the benefits of unsupervised learning?
Unsupervised learning allows for exploratory analysis and pattern discovery in large and complex datasets. It can uncover valuable insights, identify hidden structures, and help in feature engineering or preprocessing steps for supervised learning tasks. It is also useful when labeled data is scarce or expensive to obtain.