Clustering is an unsupervised learning technique that aims to group similar data points together based on their inherent similarities. It is commonly used in NLP to identify patterns and structures in text data.

Principal Component Analysis (PCA) is a dimensionality reduction technique that projects high-dimensional data into a lower-dimensional space while preserving important information. It is widely used in NLP for feature extraction and data visualization.

Latent Dirichlet Allocation (LDA) is a topic modeling technique that discovers hidden topics or themes in a collection of documents. It assumes that each document is a mixture of topics, and each topic is a distribution over words.

Word2Vec is a word embedding technique that learns vector representations of words that capture their semantic and syntactic similarities. It is widely used in NLP for various tasks such as text classification, sentiment analysis, and machine translation.

Autoencoders are unsupervised learning techniques that aim to learn a low-dimensional representation of data that preserves its intrinsic structure. They are commonly used in NLP for feature extraction, data compression, and anomaly detection.

K-Means Clustering is a clustering algorithm that partitions data points into a predefined number of clusters based on their similarities. It iteratively assigns data points to clusters and updates cluster centroids until convergence is reached.

t-SNE (t-Distributed Stochastic Neighbor Embedding) is a dimensionality reduction technique that projects data into a lower-dimensional space while preserving local distances. It is particularly useful for visualizing high-dimensional data.

Latent Dirichlet Allocation (LDA) is a topic modeling technique that discovers topics in a collection of documents and represents them as a probability distribution over words. It assumes that each document is a mixture of topics, and each topic is a distribution over words.

Word2Vec is a word embedding technique that learns vector representations of words based on their co-occurrence patterns in a large text corpus. It is widely used in NLP for various tasks such as text classification, sentiment analysis, and machine translation.

Generative Adversarial Networks (GANs) are unsupervised learning techniques that aim to generate new data samples that are similar to the training data. They consist of two neural networks, a generator, and a discriminator, that compete against each other.

Hierarchical Clustering is a clustering algorithm that builds a hierarchical tree-like structure of clusters based on the similarities between data points. It starts with each data point as a separate cluster and iteratively merges similar clusters until a single cluster is formed.

Principal Component Analysis (PCA) is a dimensionality reduction technique that projects data into a lower-dimensional space while preserving global relationships. It finds the directions of maximum variance in the data and projects the data onto these directions.

Latent Dirichlet Allocation (LDA) is a topic modeling technique that discovers topics in a collection of documents and represents them as a probability distribution over words. It assumes that each document is a mixture of topics, and each topic is a distribution over words.

ELMo (Embeddings from Language Models) is a word embedding technique that learns vector representations of words based on their syntactic dependencies in a sentence. It uses a deep neural network to learn contextualized word representations.

Autoencoders are unsupervised learning techniques that aim to learn a low-dimensional representation of data that is useful for downstream tasks. They are commonly used in NLP for feature extraction, data compression, and anomaly detection.