# LLMs: The Essential Guide

DevFeed: [LLMs: The Essential Guide](<https://devfeed.tech/articles/llms-the-essential-guide-18030.md>)

Original publisher: [Read original article](<https://blog.levelupcoding.com/p/llms-the-essential-guide>)

Author: Nikki Siapno

Published: 2026-06-26T14:44:38Z

Content type: tutorial

Language: en

Sources: [Level Up Coding System Design Newsletter](<https://devfeed.tech/sources/level-up-coding-system-design-newsletter.md>)

Topics: [Large Language Model](<https://devfeed.tech/topics/llm.md>), [systems](<https://devfeed.tech/topics/systems.md>), [tokenization](<https://devfeed.tech/topics/tokenization.md>), [Transformer](<https://devfeed.tech/topics/transformer.md>), [distributed-systems](<https://devfeed.tech/topics/distributed-systems.md>), [Inference](<https://devfeed.tech/topics/inference.md>), [Embeddings](<https://devfeed.tech/topics/embeddings.md>)

Tags: [embeddings](<https://devfeed.tech/tags/embeddings.md>), [guide](<https://devfeed.tech/tags/guide.md>), [inference](<https://devfeed.tech/tags/inference.md>), [latency](<https://devfeed.tech/tags/latency.md>), [llm](<https://devfeed.tech/tags/llm.md>), [llms](<https://devfeed.tech/tags/llms.md>), [tokenization](<https://devfeed.tech/tags/tokenization.md>), [transformers](<https://devfeed.tech/tags/transformers.md>)

## AI overview

This guide explains LLMs as distributed systems with layers including models, training pipelines, retrieval, inference infrastructure, safety layers, and product experience. It introduces how tokenization and Transformer architectures work, and connects system layers to debugging, scaling, latency, hallucinations, context loss, and cost.

## Source excerpt

Most engineers only see the API layer. Here's what's happening underneath.