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Getting Started With AI / AI Foundations

Neural Networks, LLMs and SLMs

A simple explanation of neural networks, language models, large language models, and small language models.

9 min read 100 Foundation 3/6 in module
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Why readThe Core Idea

A simple explanation of neural networks, language models, large language models, and small language models.

How to use itApply one decision rule

Use the brief to sharpen a real ai upskill conversation: what is the decision, what evidence matters, and what should remain human-led?

What to retainRemember This

Capture one design rule you would reuse when reviewing an AI workload, assistant, or operating model.

01

Executive note

The Core Idea

A neural network is a machine learning model inspired by the idea of connected processing units. It learns patterns by adjusting internal weights during training.

Modern AI uses neural networks for many tasks: image recognition, speech processing, forecasting, translation, summarization, code generation, and chat.

A language model is a neural network trained to understand and generate text. It learns statistical patterns in language and uses them to predict useful continuations.

02

Section 2 of 5

What Is an LLM?

A large language model, or LLM, is a language model trained at large scale. It usually has broad language ability, strong instruction following, and enough general knowledge to help with many tasks.

LLMs are useful for:

The trade-off is that large models can be slower, more expensive, and harder to operate in constrained environments.

  • Complex reasoning over messy context.
  • Drafting and rewriting.
  • Summarizing long material.
  • Explaining technical concepts.
  • Generating code or tests.
  • Coordinating multi-step workflows.
03

Section 3 of 5

What Is an SLM?

A small language model, or SLM, is a smaller model designed for narrower tasks, lower cost, lower latency, or deployment closer to the workload.

SLMs can work well for:

An SLM is not automatically less valuable. If the task is narrow and well-scoped, a smaller model may be the better engineering choice.

  • Classification.
  • Extraction.
  • Routing.
  • Short rewriting.
  • Domain-specific assistants.
  • High-volume tasks where speed matters.
04

Section 4 of 5

Model Routing

Model routing means sending different tasks to different models.

A practical pattern is:

This avoids using the largest model for everything and helps control cost, latency, and risk.

  • Use a small model for simple, frequent, low-risk tasks.
  • Use a larger model when ambiguity, reasoning, or synthesis increases.
  • Escalate to a human when impact or uncertainty is high.
05

Section 5 of 5

Remember This

Do not choose a model by size alone. Choose it by task quality, latency, cost, privacy needs, deployment constraints, reliability, and how easily the result can be evaluated.

Versionv1.3Updated 09 Jun 2026
MCMarius CONSTANTINESCU