Artificial neural networks (ANNs) are a type of computational model inspired by the structure and function of the human brain. They consist of interconnected nodes called artificial neurons, which process information similar to how biological neurons do. ANNs are trained on data sets and can learn to perform tasks such as image recognition, speech recognition, and natural language processing.

There are several different ANN architectures, each with its own strengths and weaknesses. Here are some of the most common architectures:

  • Feedforward neural networks: These are the simplest ANN architecture. Information flows in one direction, from the input layer to the output layer, without any loops. They are good for tasks that involve simple input-output relationships, such as classification and regression. A classic example of a feedforward neural network is the perceptron, which is a single layer network that can perform linear separation of data.
  • Convolutional neural networks (CNNs): CNNs are specifically designed for image recognition tasks. They use filters that can identify patterns in images, such as edges and corners. CNNs are very successful in applications such as facial recognition and medical image analysis. The popular AlexNet architecture is a CNN that revolutionized image recognition by achieving high accuracy on the ImageNet dataset.
  • Recurrent neural networks (RNNs): RNNs can handle sequential data, such as text or time series data. They have a feedback loop that allows them to store information from previous inputs and use it to influence their outputs. RNNs are used in applications such as machine translation and speech recognition. Long short-term memory (LSTM) networks are a type of RNN that are adept at handling long sequences of data. They are commonly used for tasks like machine translation and speech recognition.
  • Transformers: Transformers are a relatively new type of ANN architecture that have become very successful in natural language processing (NLP) tasks. They excel at modeling long-range dependencies in sequences, which is crucial for tasks like machine translation, text summarization, and question answering. Transformers have largely replaced recurrent neural networks (RNNs) as the dominant architecture for NLP tasks due to their ability to handle these tasks more efficiently. The Transformer architecture introduced by Google in 2017 has become the dominant architecture for NLP tasks. BERT (Bidirectional Encoder Representations from Transformers) is a powerful pre-trained Transformer model that can be fine-tuned for various NLP tasks.