What Are Transformer Neural Networks? 

In the field of deep learning, Transformer Neural Networks have emerged as a powerful model, especially in the area of natural language processing (NLP). TNNs, first introduced in a paper titled “Attention is All You Need” by Vaswani et al. (2017), are designed to handle sequential data, making them ideal for tasks such as machine translation and text generation.

Unlike previous sequence-to-sequence models that relied on recurrent neural networks (RNNs) or long short-term memory (LSTM) cells, TNNs use a different approach called the ‘attention mechanism’. This mechanism allows the model to focus on different parts of the input sequence when generating the output, improving the handling of long-distance dependencies.

Furthermore, TNNs also eliminate the need for sequential computation, enabling parallel processing of the input data. This feature significantly speeds up training times, making TNNs a popular choice for large-scale NLP tasks.

This is part of a series of articles about large language models

In this article:

Transformer Neural Networks Architecture 

The architecture of Transformer Neural Networks is different from conventional neural networks. It consists of four main components: an embedding layer, an encoder, a decoder, and a fully connected and softmax layer.


The embedding layer acts as the entry point for input data, typically words or sub-words known as tokens. Its primary function is to transform each token in the input sequence into a fixed-size vector, commonly referred to as an embedding. These vectors encapsulate the semantic nuances of the words, such that words or tokens with similar meanings tend to be mapped to close vectors in the embedding space.

In the transformer model, the embedding layer has two types of embeddings. The first is token embeddings, where every word or sub-word in the sequence is associated with a unique vector based on its semantic value. The second is positional embeddings, which compensates for the transformer’s inherent lack of sequential awareness. Given that transformers do not natively recognize order or sequence, positional embeddings provide vital information about each word’s position within a given sequence.

Learn more in our detailed guide to embeddings machine learning (coming soon)


The encoder’s role in a TNN is to understand and represent the input data. It comprises a stack of identical layers, each containing two sub-layers. The first is a multi-head self-attention mechanism, and the second is a simple, position-wise fully connected feed-forward network. A residual connection surrounds each of the two sub-layers, followed by layer normalization.

A crucial aspect of the encoder is the self-attention mechanism. This mechanism allows the model to weigh the relevance of each word in the input sequence in relation to every other word. It gives the model the ability to understand the context and the relationships between words, which is vital for complex NLP tasks.


Following the encoder is the decoder, which also consists of a stack of identical layers. However, in addition to the two sub-layers found in the encoder, the decoder has a third sub-layer which performs multi-head attention over the encoder’s output. This structure allows the decoder to generate the output sequence based on the encoded input and its own internal state.

Like in the encoder, each sub-layer in the decoder is surrounded by a residual connection and followed by layer normalization. The output of the last decoder layer is then fed into the final linear and softmax layer.

Fully Connected Layer

The final component of the TNN architecture is a traditional, fully connected neural network that maps the decoder’s output to a set of predicted output tokens. Following this, a softmax layer converts these scores into probabilities, with each probability indicating the likelihood of a particular token being the next word in the sequence.

Examples of Transformer Neural Networks 

Transformer Neural Networks are a relatively new entrant in the field of deep learning. Introduced in 2017, these networks have quickly become a cornerstone in a myriad of applications, from natural language processing to computer vision.


BERT, which stands for Bidirectional Encoder Representations from Transformers, is designed to pre-train deep bidirectional representations from unlabeled text by jointly conditioning on both left and right context in all layers. As a result, the pre-trained BERT model can be fine-tuned with just one additional output layer to create state-of-the-art models for a wide range of tasks.

BERT’s prowess lies in its ability to understand the context of a word based on its surroundings. This bidirectional understanding is a significant development in the world of natural language processing, where the meaning of a word can often change based on its contextual use. BERT’s architecture, which incorporates a transformer, allows it to understand this context and provide more accurate results. It is worth noting that BERT is now a core part of the Google search engine.


Next on our list of Transformer Neural Networks is GPT, or Generative Pre-Training Transformer. GPT, like BERT, leverages the power of transformer networks, but with a twist. Whereas BERT is bidirectional, meaning it considers context from both the left and the right of a word, GPT is unidirectional, considering only the context to the left of the word.

Despite this, GPT has proven to be very powerful in a range of applications. It’s particularly adept at tasks that involve generating text, such as writing an essay or creating a summary. Recent generations of GPT, in particular GPT 3.5 and GPT 4, represent a global breakthrough in the cognitive capabilities of AI models.


T5, or Text-to-Text Transfer Transformer, is based on the idea of converting every problem into a text-to-text format, regardless of the task at hand. This could involve tasks like translation (translating English text to French), summarization (creating a summary of a long document), or even classification (classifying a document into one of several categories).

The power of T5 comes from its flexibility. By converting every problem into a text-to-text format, T5 can leverage the same model, loss function, and hyperparameters across a wide range of tasks.


XLNet, like BERT, is a bidirectional model, meaning it considers context from both the left and the right of a word. However, XLNet differs from BERT in one crucial way: it does not use a fixed-length context.

This makes XLNet very powerful, as it can consider a theoretically infinite context. This is particularly beneficial for tasks that involve long documents or sequences, where the context might span thousands of words. By considering this extended context, XLNet can provide accurate and nuanced results.

It is worth noting that GPT and comparable models are now providing larger context sizes, up to 100,000 tokens in some cases, which allow them to provide superior performance to XLNet, even for very large inputs.

Transformer Neural Networks Applications 

TNNs have found widespread application in several areas of NLP, thanks to their ability to handle sequential data and their scalability.

Machine Translation

Perhaps the most popular use of TNNs is in machine translation, where the task is to convert text from one language to another. TNNs excel at this task because of their ability to understand the context and relationships between words in a sentence. This is crucial for accurate translation.

Text Generation

Another application of TNNs is in text generation. Whether it’s generating a continuation of a given text, auto-completing code in various programming languages, or generating a meaningful response in a conversation, TNNs’ ability to model the complex relationships between words and their context makes them well-suited for these tasks.

Question Answering Systems

TNNs are also used in question answering systems, where the task is to provide a correct answer to a given question based on a provided context. The attention mechanism of TNNs allows them to focus on the relevant parts of the context when generating the answer, leading to more accurate results.

Speech Recognition

Finally, TNNs are also finding use in speech recognition systems. By treating the audio signal as a sequence of data, TNNs can be used to transcribe spoken words into written text, with impressive accuracy.

Transformer Neural Networks Challenges and Limitations 

Despite their impressive capabilities, TNNs are not without their challenges and limitations.

Model Complexity and Computational Demands

One of the main issues with TNNs is their model complexity and high computational demands. Training a TNN requires a significant amount of computational resources, which can make them inaccessible for those without access to high-end hardware.

Difficulty in Interpretation and Explainability

Another challenge with TNNs is their lack of interpretability. While the attention mechanism provides some insight into what the model is focusing on, it is still largely a black-box model. This makes it difficult to understand why the model made a certain prediction, which can be problematic in situations where explainability is important.

Bias and Ethical Concerns

Finally, TNNs can suffer from bias in their predictions. If the training data contains biases, the model will likely learn and reproduce these biases in its predictions. This raises ethical concerns, especially when TNNs are used in sensitive applications such as hiring or loan approval.

The Role of Transformers in the AI Revolution

AI has taken huge strides forward in the 2020s, and much of this progress has been driven by the transformer model. Transformers are a cornerstone of modern AI systems, especially in the domain of natural language processing.

At the forefront of this transformation is the role transformers play in powering large language models (LLMs). Models like BERT, GPT-3, andGPT-4 base their impressive performance on the backbone provided by the transformer architecture. This unique design, characterized by its parallel processing capabilities, allows these models to scale up, accommodating millions or even billions of parameters. Such massive scaling has ushered in an era of models that possess an uncanny ability to understand and generate text that mirrors human language. 

Additionally, the inherent structure of transformers facilitates pre-training on huge datasets, and can be tuned for a variety of specific tasks, ranging from translation to summarization to new text generation. This flexibility means that the base transformer model can serve diverse applications, promoting both efficiency and broader applicability.

In parallel, transformers have catalyzed the evolution of advanced AI chatbots. Platforms like ChatGPT demonstrate the potential of these networks, capable of engaging in real-time, contextually rich conversations with users, assisting in creative writing, and even writing functional code in any programming language. Owing to the self-attention mechanism at the core of the transformer architecture, chatbots can retain and utilize conversation context, leading to responses that resonate with relevance and coherence. 

Further enriching the AI landscape is the enthusiastic embrace of transformers by the global AI community. The surge in open-source tools, comprehensive libraries, and readily available pre-trained models has democratized access to cutting-edge AI solutions. This spirit of shared learning and collaboration is setting the stage for more revolutionary innovations in the very near future.

Transformer Neural Networks with Swimm

Transformer Neural Networks (TNNs) have fundamentally changed the landscape of Natural Language Processing (NLP), machine translation, and numerous other AI applications. Their architecture enables unparalleled flexibility and the capacity to understand and generate contextually rich text. However, as revolutionary as TNNs are, their complexity can be a stumbling block for development teams aiming to integrate or build upon them.

That’s where Swimm comes into play. Using its robust solution to the challenges of developer onboarding and knowledge sharing, distinguished engineers and senior developers can easily create and maintain detailed, code-coupled documentation. They can capture their deep insights about the transformer architecture or a specific implementation like BERT or GPT, and make that knowledge readily accessible to the rest of the team. This not only improves team productivity but also enhances code quality by ensuring everyone is aligned on best practices and intricate details.

So, whether you’re a director aiming for team efficiency, a seasoned engineer sharing nuanced technical expertise, or an entry-level developer eager to dive into the world of transformers, Swimm offers the toolkit to make that journey significantly more manageable and productive. Let’s dive in together. 

Get started with Swimm today!