Introduction to LLMs for Developers: Tokens, Prompts, Context Windows, and First AI Apps

Ashutosh Piprode — Wed, 20 May 2026 05:28:39 +0000

Build Your First LLM Product: A Practical Guide for Developers

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In this article, we will take you through the process of building your first LLM (Large Language Model) product. We will cover the basics of LLMs, their types, and how to use them to create a real-world application. By the end of this article, you will have a solid understanding of LLMs and be able to build your own LLM product.

Introduction to LLMs

What are LLMs?

LLMs are a type of artificial intelligence model that can understand and generate human-like language. They come in several flavors:

Base models: Similar to autocomplete functionality, these models are better for fine-tuning to learn a new skill.
Chat/Instruct models: These models are chatbots that are good at making conversations.
Reasoning/Thinking models: These models are reasoning models that are good at problem-solving.
Hybrid models: A combination of Chat/Instruct models and Thinking/Reasoning models.

Example Use Cases for LLMs

Some examples of LLMs in action include:

Virtual assistants, such as Siri or Alexa
Chatbots on websites or social media platforms
Automated content generation, such as news articles or blog posts
Language translation apps

Key Concepts in LLMs

Synthesizing Information

LLMs can answer questions in depth with a structured, well-researched answer and often include a summary.

Fleshing out a Skeleton

LLMs can form a couple of notes, building out a well-crafted email, or a blog post, and iterating on it until perfect.

Coding

LLMs have the ability to write and debug code, making them a valuable resource for engineers.

How LLMs Work

Tokens and Context Window

LLMs use tokens, which are pieces of text that can be small or big, as inputs. The context window is the maximum amount of data that can be passed in a single request to an LLM.

Stateless Nature of LLMs

Every individual call to an LLM is stateless, meaning that we pass in the whole conversation so far to help it understand the entire context.

Input Types

LLMs are trained on mostly three types of inputs: Natural Languages like English, Markdowns, and JSON.

Prompting LLMs

One Shot Prompting

Giving the LLM an example of how the output should look like is called one shot prompting.

Mult-ishot Prompting

Giving multiple examples is called mult-ishot prompting.

Defining Agents

LLM Agents

An LLM agent can control the workflow, run tools in a loop to achieve goals, and have memory, planning, autonomy, and LLM orchestration via tools.

Building Your First LLM Product

Step 1: Choose an LLM Type

Choose the type of LLM that best fits your use case. Consider the following factors:

The complexity of the task you want the LLM to perform
The amount of data you have available for training
The level of customization you need

Step 2: Define Your Prompt

Define a clear and concise prompt that the LLM can understand. This includes:

Providing context for the task
Specifying the output format
Giving examples of the desired output

Step 3: Test and Refine

Test your LLM product and refine it as needed. This includes:

Evaluating the accuracy of the output
Adjusting the prompt or training data as needed
Continuously testing and refining the model

Takeaways

LLMs are powerful tools for generating human-like language
Choosing the right LLM type and defining a clear prompt are crucial for success
Testing and refining your LLM product is an ongoing process
LLMs can be used for a variety of tasks, including content generation, language translation, and coding

Example Code

import gradio as gr

# Define the LLM model
model = ...

# Define the prompt
prompt = "Write a short story about a character who..."

# Create a Gradio interface
demo = gr.Interface(
    fn=model,
    inputs="text",
    outputs="text",
    title="LLM Story Generator",
    description="Generate a short story using an LLM",
)

# Launch the interface
demo.launch()

Conclusion

Building your first LLM product can seem daunting, but with the right guidance, it can be a rewarding experience. By following the steps outlined in this article, you can create a practical and useful LLM product. Remember to choose the right LLM type, define a clear prompt, and test and refine your product continuously.

Important Considerations

Accuracy and Bias: The accuracy of LLMs can vary depending on the quality of the training data. LLMs can be biased if the training data is biased.
Ethical Concerns: The use of LLMs raises ethical concerns, such as the potential for job displacement and the need for transparency in decision-making.

Suggested DEV.to Tags

LLM
Large Language Model
AI
Machine Learning
Natural Language Processing
Gradio

DEV Community: Ashutosh Piprode