Neural Machine Translation – A Powerful Tool, Different Types And How It Works

by | Jan 4, 2023 | Natural Language Processing

Neural machine translation (NMT) is a state-of-the-art technique for translation. Our previous article on translating text in Python covered the two most common ways of getting started with translations. The first was utilising an API like Google Translate. These services tend to all implement NMT and are more accurate than the other models discussed in the article. This article covers the basics of neural machine translation, how it works, the different types and the libraries you can use to implement these techniques.

What is neural machine translation?

A neural network is used in neural machine translation (NMT), translating text from one language to another. NMT systems predict the best translation for a given input sentence after training on large data. As a result, they can work with various languages and frequently produce more precise and sound natural translations than those made by earlier machine translation techniques. NMT systems, which are used a lot in business, make up a big part of research in natural language processing.

accurate translation with neural machine translation

NMT: the state-of-the-art in machine translation

How does neural machine translation work?

To translate text from one language to another, neural machine translation (NMT) employs a neural network. After training on a large set of translations, the neural network learns to guess the most likely translation for a given sentence.

During training, an input sentence in one language and its translation in a different language are presented to the NMT system. This illustration helps the system understand the relationships and patterns between the words and phrases in the two languages.

Once trained, the NMT system can translate a sentence input in one language into another using the learned information. This is accomplished by dividing the input sentence into smaller components, such as words or phrases, and feeding these components to the neural network as input. The network then uses its prediction of the most likely translation to make a sentence in the other language.

NMT systems can be used to translate text from many different languages. In addition, they often produce more accurate and grammatically correct translations than older machine translation techniques.

What are the types of neural machine translation?

Text can be translated from one language to another using various neural machine translation (NMT) systems. NMT systems come in a variety of popular configurations.

Encoder-decoder models

A neural machine translation (NMT) system known as an encoder-decoder model consists of two neural networks: an encoder and a decoder. The encoder reads the text as input and transforms it into a collection of continuous representations (called embeddings) that capture the text’s meaning. The decoder uses these representations to produce the translated output.

One of the most popular NMT system types, encoder-decoder models, has succeeded with many translation tasks. To produce the output, they first encode the input text into a continuous representation and then sent it to the decoder. The encoder-decoder architecture is frequently used with attention mechanisms to enable the decoder to concentrate on particular parts of the input text while producing the output. Most of the time, recurrent neural networks (RNNs) or convolutional neural networks (CNNs) are used to build the encoder and decoder.

The versatility of encoder-decoder models and their strong performance on many translation tasks are two of their many benefits. They can, however, be computationally demanding and may need help with lengthy input sequences.

Transformer models

Transformer models are a subset of neural machine translation (NMT) systems that process input text and produce translations using self-attentional mechanisms. As an encoder-decoder model, they have two neural networks: an encoder that analyses the input text and a decoder that produces the translated output.

Transformer models were first discussed in the article “Attention is All You Need” (Vaswani et al., 2017). They have recently gained popularity due to their capacity for handling longer sequences and successfully completing various translation tasks. They function by continuously representing the input text using self-attention mechanisms to weigh the significance of different text parts. After that, the decoder receives this representation and produces the translated output.

Transformer models are more effective than other encoder-decoder models because they can parallelize the computation of the self-attention mechanisms. This is one of their main advantages. They have also demonstrated strong performance on various translation tasks, making them a cutting-edge model for NMT. Even so, they can be computationally demanding and may have trouble processing extremely long input sequences.

Attention-based models

Neural machine translation (NMT) systems that use attention mechanisms to focus on various portions of the input text while producing the output are known as attention-based models. This can improve the quality of the translation and help the model handle input sequences that are more difficult and longer.

An encoder neural network processes the input text, and a decoder neural network produces the translated output. Attention-based models are a type of encoder-decoder model. The attention mechanism weights the importance of various sections of the input text. This creates a weighted sum of the input representations sent to the decoder. This enhances the quality of the translation by enabling the decoder to concentrate on particular portions of the input text while producing the output.

Given their success in numerous translation tasks, attention-based models are now popular for NMT systems. They are also more efficient than other encoder-decoder models and can handle longer input sequences better. Still, they can be hard to programme and require help with long input sequences.

Hybrid models

Hybrid models are neural machine translation (NMT) systems that combine various models or techniques to improve translation performance. You can use hybrid models to make up for the flaws of different NMT models or to add more data or processing steps to the translation process.

Hybrid models can be built in various ways, and the particular design of a hybrid model will depend on the goals of the model and the specific tasks it is intended to carry out. Various hybrid modelling instances include:

  • Ensemble models are NMT systems that combine the results of various separate NMT models to create a final translation. Combining the advantages of multiple models can enhance translation quality while lowering the possibility of bias or error in any one model.
  • Hybrid models that combine various NMT model types: To enhance performance, these NMT systems combine different NMT model types, such as encoder-decoder and attention-based models.
  • Hybrid models with extra processing steps: These NMT systems add additional processing steps, like post-processing or error correction, to improve the output’s quality or fluency.

Hybrid models can improve translation performance by a significant amount, but they can also be harder to design and set up than other NMT systems.

Machine learning libraries for NMT

Neural machine translation (NMT) systems can be implemented using a variety of machine learning libraries. The most well-liked NMT libraries include:

  • TensorFlow: NMT systems can be implemented using this well-liked open-source machine learning library. It can be used to implement a wide range of NMT architectures and offers a variety of tools and libraries for creating, honing, and evaluating machine learning models.
  • Keras: On top of TensorFlow, Keras is a high-level machine learning library. It offers a straightforward, user-friendly interface for creating and refining machine learning models. It can put NMT systems into practice using either the sequential model or the functional API.
  • PyTorch: PyTorch is another free machine learning library that can be used to implement NMT systems. It emphasises deep learning and provides tools and libraries for building, training, and evaluating machine learning models.
  • OpenNMT is an open-source NMT library that offers resources for developing and testing NMT models. It can be used to train unique models on sizable translation datasets and comes with various pre-trained models.

Other machine learning libraries can also be used to implement NMT systems. The one you choose will depend on the specifications and objectives of the NMT system being developed.


Text is translated from one language to another using neural networks in a neural machine translation (NMT) process. Encoder-decoder, transformer, attention-based, and hybrid models are just a few of the different NMT systems developed. Many machine learning libraries and frameworks, including TensorFlow, Keras, and OpenNMT, can be used to implement these systems. NMT systems are now crucial for enhancing language translation because they are effective at various translation tasks.

Have you decided to implement your translation system, or are you using an API that already implements this? Let us know in the comments.

About the Author

Neri Van Otten

Neri Van Otten

Neri Van Otten is the founder of Spot Intelligence, a machine learning engineer with over 12 years of experience specialising in Natural Language Processing (NLP) and deep learning innovation. Dedicated to making your projects succeed.

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