Definition

What is AI inference?

Sean Michael Kerner

AI inference is the process during which a trained artificial intelligence model applies its understanding to generate original output in real time.

In an inference operation, a model responds with its trained knowledge. More importantly, it also reasons to produce new content and solutions. With AI inference, a trained AI model evaluates live data to make a prediction or solve a task. This critical phase determines the effectiveness of AI models in practical applications, ranging from common AI tasks, such as speech recognition using natural language processing (NLP) to image generation and object identification using machine vision.

Differences between AI inference and machine learning

Machine learning (ML) builds systems that acquire knowledge from data. As with AI, there are multiple stages of an ML process. Typically, the two main operations are training and inference. With ML inference, the underlying algorithm in the ML model seeks to recognize patterns and make predictions.

AI has training and inference stages, too. While ML inference makes predictions based on pattern recognition for large data sets, AI inference employs its trained model to process previously unseen data and generate entirely new outputs.

AI inference vs. AI training

In AI, there are fundamentally two core operations: training and inference. Each operation has its purpose and set of requirements.

Aspect	AI training	AI inference
Definition	Process of teaching an AI model to recognize patterns and make predictions using large data sets	Process of using a trained AI model to generate outputs or make decisions based on new data
Purpose	To create and refine AI models for specific tasks	To apply trained models to real-world problems and generate actionable insights
Data used	Large, labeled data sets -- training data	New, unseen input data
Computational intensity	Extremely resource-intensive, often requiring distributed computing	Less resource-intensive, optimized for efficiency and speed
Hardware requirements	High-performance graphics processing units (GPUs), tensor processing units or specialized AI accelerators	Various hardware, from powerful GPUs to central processing units (CPUs), edge devices or specialized inference accelerators
Time frame	Can take hours, days or even weeks for complex models	Usually occurs in real time or near -real time -- milliseconds to seconds
Frequency	Performed periodically to create or update models	Continuous process in deployed applications
Key challenges	Acquiring quality training data, preventing overfitting, managing computational costs, performing hyperparameter tuning	Reducing latency, optimizing for different hardware, maintaining accuracy, scaling to handle multiple requests
Output	A trained AI model with optimized parameters	Predictions, decisions, classifications or generated content
Typical applications	Developing large language models, machine vision systems and recommendation engines	Developing chatbots, real-time object detection, fraud detection, self-driving cars and personalized content delivery
Role in AI lifecycle	Initial development and periodic refinement phase	Operational phase during which the model provides value
Scalability concerns	Scaling to handle massive data sets and increasingly complex models	Scaling to handle high volumes of simultaneous inference requests
Privacy considerations	Requires access to large amounts of potentially sensitive data	Often performed on the device or at the edge, enhancing data privacy

How does AI inference work?

AI inference follows several steps that enable a trained AI model to process new data and generate outputs:

Model preparation. An AI model is trained on a large data set. The model encodes relationships and patterns from the training data into its weights or parameters.
Model deployment. The trained AI model is deployed in an environment -- cloud server, edge device or app -- where it processes new data.
Hardware selection. The model is deployed on appropriate hardware. While CPUs handle inference tasks, GPUs are preferred for their parallel processing capabilities, which accelerate AI inference operations.
Framework selection. An ML framework, such as the open source TensorFlow or PyTorch technologies, provides tools and libraries that optimize the inference process.
Inference initiation. A user or system sends a query or new data to the trained model for processing. The model receives new, real-time data as input.
Weight application. The model applies its stored weights to the input data, which represents the knowledge learned during training. This phase is sometimes referred to as the forward pass, when the model applies its learned parameters to the new data or prompt.
Computation. The model performs calculations based on its architecture and learned weights. For neural networks, this involves matrix multiplications and activation functions.
Output generation. Based on its computations, the model produces an output -- a classification, prediction or generated content, depending on the model's purpose.
Postprocessing. Postprocessing refines raw output, making it more interpretable or actionable. This step involves converting probabilities to class labels, formatting text or even using guardrails to ensure the generated information does not violate privacy or security policies.
Result delivery. The final output is delivered to the user or system that requested the inference. This is displayed in an application, stored in a database or used to trigger further actions.

Why is AI inference important?

AI inference is the mechanism that transforms mathematical models into practical, real-world tools that provide insight, enhance decision-making, improve customer experiences and automate routine tasks. Inference is a critical aspect of AI operations for many reasons, including the following:

Practical applications. Inference is the "moment of truth" for AI models, when trained models are put to work on real-time data.
Business value. Fast and accurate inference enables businesses to make timely decisions, automate processes and provide AI-powered services to customers, directly translating AI capabilities into business value.
Operations. AI models are typically in inference mode, making inference the primary focus for optimizing AI systems in production environments.
Cost. While training is a one-time investment, inference costs accumulate over time. For businesses deploying AI at scale -- running millions of chatbot interactions daily, for example -- inference efficiency directly impacts operational expenses.
Environmental impact. Inference drives an AI model's carbon footprint. Improving inference efficiency reduces the environmental impact of AI technologies.
User experience. Faster inference leads to more responsive applications and better user satisfaction.
Software optimization. Inference challenges drive innovations in model compression techniques, middleware improvements and runtime optimizations, enhancing performance.

Types of AI inference

Among the most common types of AI inference are the following:

Batch inference. Batch inference processes large volumes of data offline in groups or batches, typically when real-time results are not required. For example, a retail company analyzes customer purchase data overnight to generate personalized product recommendations the next day.
Real-time inference. Data is processed as it arrives, providing immediate results. For example, a chatbot responding to user queries in real-time uses NLP models to understand and generate appropriate responses.
Edge inference. Edge inference occurs on local devices -- those in proximity to the location of the generated data -- reducing latency and enhancing privacy. For example, a smart home security camera using on-device AI detects and alerts homeowners about potential intruders without sending video data to the cloud.
Probabilistic inference. Probabilistic inference, also known as statistical inference, estimates probabilities and uncertainties and is often used in decision-making systems. For example, a weather forecasting system predicts the likelihood of rain based on various atmospheric conditions.
Predictive inference. Predictive inference uses historical data to forecast future events or outcomes. For example, a financial model predicts stock prices based on past market trends and current economic indicators.
Rule-based inference. Rule-based inference applies predefined logical rules to make decisions or draw conclusions. For example, a trained AI system diagnoses car problems based on a set of if-then rules derived from an expert mechanic's knowledge.
Machine vision inference. This type of inference interprets and analyzes visual data from images or videos. For example, an autonomous vehicle uses object detection models to identify pedestrians, traffic signs and other vehicles in real time.
NLP inference. NLP inference involves understanding and generating human language. For example, a language translation app instantly translates spoken words from one language to another.

Benefits of AI inference

AI inference delivers advantages across multiple areas, including the following:

Real-time decision-making. Enables instant responses to complex queries.
Personalized user experiences. Affords on-the-fly customization of content and services.
AI accessibility. Makes AI capabilities accessible via cloud and endpoint devices.
Enhanced user interface. Employs natural and intuitive interfaces through real-time processing.
Improved operational efficiency. Automates and optimizes complex processes in real time.

Problems with AI inference

While AI inference provides many benefits in various fields, its application generates concerns that require attention. Among the key issues are the following:

Cost. Inference is resource-intensive, especially for large models, which raises operational costs.
Environmental impact. Inference processes consume energy, inflating carbon emissions.
Latency. Real-time applications require low-latency inference, which is difficult to achieve.
Data privacy concerns. Handling sensitive data in real time highlights privacy issues.
Model explainability. Complex deep learning models are often tough to interpret, making it difficult to understand AI inference decisions.