Long short-term memory (LSTM) networks for dummies

One of the most widely used and powerful types of neural networks is the Long Short-Term Memory (LSTM) network.

This article will break down what LSTM networks are, how they work, and where they are used, all in a simple and easy-to-understand manner.

What are LSTM networks?

Long Short-Term Memory (LSTM) networks are a type of Recurrent Neural Network (RNN). RNNs are specialized neural networks designed to process sequences of data, such as time-series data, text, or even video.

However, traditional RNNs have limitations when it comes to learning long-term dependencies or relationships between elements in a sequence.

LSTM networks address this issue by incorporating a memory mechanism, allowing them to retain information over longer periods.

The Building Blocks of LSTM networks

The core building block of an LSTM network is the LSTM cell. Unlike standard RNN cells, LSTM cells have a unique structure that allows them to store and manipulate information over time. The primary components of an LSTM cell are:

  • Input gate: Decides how much of the new input will be added to the cell’s memory.
  • Forget gate: Determines which information should be discarded from the cell’s memory.
  • Cell state: The memory of the LSTM cell, storing important information over time.
  • Output gate: Controls how much of the current memory will be output to the next layer or the next cell in the sequence.

These gates and the cell state work together to decide what information to keep, discard, and pass on, enabling the LSTM network to learn long-term dependencies effectively.

How do LSTM networks work?

An LSTM network processes a sequence of data one element at a time, updating its internal memory based on the input and the previous memory state. It does so by using the input, forget, and output gates to selectively store, discard, or propagate information.

For example, when analyzing a sentence, an LSTM network can remember important words or context from earlier parts of the sentence and use that information to better understand the meaning of subsequent words.

This ability to learn long-term dependencies makes LSTM networks highly effective for tasks that require understanding complex patterns in sequences.

Applications of LSTM networks

LSTM networks have found success in various applications, including:

  • Natural language processing (NLP): LSTMs are widely used for tasks such as machine translation, sentiment analysis, and text summarization.
  • Speech recognition: LSTM networks can be used to convert spoken language into written text by learning to recognize the patterns in the audio signal.
  • Time-series prediction: LSTMs can analyze historical data, such as stock prices, and make predictions about future trends.
  • Video analysis: LSTM networks can process video data by analyzing the temporal relationships between frames, enabling applications like action recognition and video summarization.


Long Short-Term Memory (LSTM) networks are a powerful type of neural network that overcomes the limitations of traditional RNNs when dealing with long-term dependencies in sequence data.

By incorporating memory mechanisms, LSTM networks can effectively learn complex patterns, making them highly useful for a wide range of applications.

With their ability to process and analyze vast amounts of sequential data, LSTM networks continue to push the boundaries of what AI and machine learning can achieve.

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