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Reference · AI Foundations

What Is Generative AI? IBM's Explainer, in Bullet Points

The three phases that turn raw data into a working application, the four model architectures and when each one arrived, what agents add on top, the risks that are named rather than glossed over, and a timeline that starts in 1906.

15 September 2026 · Summary · 9 minute read
Source

This is my summary of IBM's explainer What is generative AI?, written by Cole Stryker and Mark Scapicchio for IBM Think. Every figure and date below comes from that page. Read the original for the full treatment.

3
Phases
4
Architectures
6
Named risks
1906
Timeline starts

The whole article on one screen

Read time 9 min · Scan time 40 sec
How a working application gets built

1. Training

Terabytes of unlabelled internet text. Millions of fill-in-the-blank exercises. Output is a foundation model.

Millions of dollars · weeks
→

2. Tuning

Narrow the generalist to your task, with labelled data (fine tuning) or human scoring (RLHF).

Labour, not compute
→

3. Generate & retune

A loop, not a finish line. Add RAG to reach live sources the training data never saw.

Retuned weekly
Four architectures, four years
2013

VAEs

Compress, then decode many variations. Anomaly detection.

2014

GANs

Two networks compete. Style transfer, data augmentation.

2014

Diffusion

Add noise, learn to remove it. DALL-E runs on this.

2017

Transformers

Attention across a whole sequence. ChatGPT, Copilot, Gemini.

What it makes, and what goes wrong

Creates

TextImagesVideo Speech & musicCodeDesign & art Synthetic data

Six named risks

HallucinationsInconsistent outputBias No explainabilityNo agreed metricsSecurity & IP Deepfakes
It did not start in 2022
1906
Markov Chain
1964
ELIZA, first chatbot
1999
First GPU
2004
Google autocomplete
2013
VAEs
2014
GANs, diffusion
2017
Transformer paper
2020
GPT-3
2022
ChatGPT

What this covers

  1. What generative AI is
  2. The three phases
  3. Foundation models and LLMs
  4. The four architectures
  5. What it can create
  6. The benefits claimed
  7. Use cases by business area
  8. Agents and agentic AI
  9. Risks and limitations
  10. The timeline
  11. Watch it explained
Section 01

What generative AI is

The definition IBM settles on, and the two adoption figures it uses to size the shift.

Section 02

The three phases

This is the part most explainers skip. A working application is not one step, it is three, and each one runs on a different clock.

01

Training

A deep learning algorithm runs millions of fill-in-the-blank exercises over terabytes of raw, unlabelled data pulled from the internet, predicting the next word, the next element of an image or the next command in code, adjusting each time to close the gap.

02

Tuning

The foundation model is a generalist that knows a lot about many things and cannot hit the accuracy a specific task needs. Tuning narrows it, either with labelled application-specific data or with human feedback.

03

Generation, evaluation, retuning

An ongoing loop rather than a finish line. Applications get retuned as often as once a week. The foundation model underneath updates perhaps every year or 18 months.

Section 03

Foundation models and LLMs

Section 04

The four architectures

Four designs, arriving across four years, each still in use for different jobs. The one everybody talks about is the last.

ArchitectureHow it worksWhat it is good at
VAEs2013 Two networks paired. One compresses unlabelled data into parameters, the other decodes those parameters back into content. A variational autoencoder decodes multiple new variations, so it can close in on higher fidelity over time. Anomaly detection, including medical image analysis, and natural language generation. Credited with breakthroughs in image recognition and NLP.
GANs2014 Two networks compete. A generator produces new content and a discriminator judges its accuracy and quality. Image and video generation. Particularly strong at style transfer, such as turning a photo into a pencil sketch, and at data augmentation to widen a training set.
Diffusion2014 Noise is added to training data until it is unrecognisable, then the algorithm learns to diffuse that noise back toward a desired output, step by step. Slower to train than VAEs or GANs, and repaid with finer control and higher-quality images. DALL-E runs on a diffusion model.
Transformers2017 Documented in the paper Attention is All You Need by Ashish Vaswani and colleagues. Attention identifies what matters most inside a sequence, so whole sentences process at once rather than word by word. Most of the tools you know: ChatGPT, GPT-4, Copilot, BERT, Bard and Midjourney. Best at longer output such as articles and papers, and can be tuned to use tools like spreadsheets or HTML.
Why transformers won

They capture context across a whole sequence instead of a word at a time, they train faster because they process in parallel, and they encode training data into embeddings that carry both the data and its context. That combination is what made long, coherent output possible.

Section 05

What it can create

Section 06

The benefits claimed

Five, with efficiency sitting above the rest.

Section 07

Use cases by business area

Section 08

Agents and agentic AI

Section 09

Risks and limitations

Six, named plainly. This is the section to read twice before you put anything in front of a customer.

The line worth carrying into a meeting

A black-box model that cannot show its reasoning is a problem long before it is wrong. If nobody can explain how a result was reached, nobody can tell a legitimate decision from a biased one.

Section 10

The timeline

Generative AI did not start in 2022. IBM traces it back more than a century.

Section 11

Watch it explained

Eight lectures, ordered easiest first, chosen because they explain this without assuming you write code. Press Summary on any card to read what it covers before you spend the time. Those bullet points were written from each video's own captions, not from its title.

Generative AI Explained in 2 Minutes Start here2 min

Generative AI Explained in 2 Minutes

KI-Campus

The shortest honest explanation on this list. If a colleague has two minutes, this is the one.

Watch ↗
AI, Machine Learning, Deep Learning and Generative AI Explained Easy10 min

AI, Machine Learning, Deep Learning and Generative AI Explained

IBM Technology

Sorts out the four words everyone uses interchangeably. Watch this before anything else if the vocabulary is the problem.

Watch ↗
Large Language Models, Explained Briefly Easy, visual8 min

Large Language Models, Explained Briefly

3Blue1Brown

The clearest mental model on this page, and the two scale comparisons are the ones your audience will repeat afterwards.

Watch ↗
What Are Generative AI Models? Easy9 min

What Are Generative AI Models?

IBM Technology, Kate Soule

The best explanation of foundation models, and unusually candid about the two disadvantages.

Watch ↗
How Large Language Models Work Easy6 min

How Large Language Models Work

IBM Technology

Turns the numbers into units you can picture, and ends on what businesses do with it in practice.

Watch ↗
Introduction to Generative AI Easy22 min

Introduction to Generative AI

Google Cloud

Carries the single most useful test on this page for telling generative AI from ordinary AI.

Watch ↗
Non-Technical Intro to Generative AI Deeper, still non-technicalFull course

Non-Technical Intro to Generative AI

freeCodeCamp.org

The one to send someone who wants the whole picture, including the ethics, without any maths.

Watch ↗
Transformers, the Tech Behind LLMs Go deeper27 min

Transformers, the Tech Behind LLMs

3Blue1Brown

Watch when the shorter ones leave you wanting to see inside. Entirely visual, no code.

Watch ↗
If you only have ten minutes

Watch the two-minute KI-Campus explainer for the shape of it, then the IBM nesting-doll video for the vocabulary. That pair covers enough to follow any conversation about this at work.

Read the original

This summary condenses a long reference page into what a working professional needs to hold in their head. The full article carries more detail on each architecture, the product links, and IBM's own tooling.