Scrolls
6 min read
On this page

Levels of Abstraction

Different people need different levels of detail about the same thing. A CEO looks at revenue numbers. A manager looks at team performance. An engineer looks at code. They are all looking at the same company, but at different levels of abstraction.

This chapter explores how levels of abstraction work, why the right level depends on your role and purpose, and how systems in both everyday life and technology are organized into layers.

The Same Thing, Different Views

Consider a house. Different people see it at different levels of detail:

  • The buyer sees bedrooms, bathrooms, square footage, and price. They want to know if it fits their family and budget.
  • The real estate agent sees comparable sales, neighborhood trends, and marketing angles.
  • The architect sees load-bearing walls, structural materials, and building code compliance.
  • The electrician sees wiring runs, circuit breaker capacity, and outlet placement.
  • The plumber sees pipe diameters, water pressure, and drainage slopes.

No one is seeing the "wrong" house. They are all looking at the same house through the lens of what matters for their job. Each person operates at the level of abstraction appropriate for their role.

Why Levels Matter

Making decisions at the right altitude

A CEO who tries to make decisions at the code level will get lost in details and miss the big picture. An engineer who tries to make decisions at the revenue level will lack the information they need to write correct software.

Each level of abstraction supports a different kind of decision:

Level               Decisions Made
--------------------------------------------------
Executive           Strategy, investment, direction
Manager             Priorities, staffing, timelines
Team Lead           Architecture, tool choices
Engineer            Implementation, algorithms

Moving between levels is a skill. The best leaders can zoom in to understand technical details when needed and zoom back out to see the strategic picture. The best engineers can zoom out to understand business context and zoom back in to write precise code.

Communicating effectively

When you speak to someone at the wrong level of abstraction, communication breaks down.

If you ask your mechanic what is wrong with your car and they say "the crankshaft position sensor is sending intermittent signals that cause the ECU to miscalculate ignition timing," that might be accurate but unhelpful. What you needed to hear was "there is a sensor problem that makes the engine run rough — it'll cost about $300 to fix."

The mechanic's detailed explanation is not wrong. It is just at the wrong level for you.

Everyday Examples

Cooking

High level:    "We're having Italian tonight."
Mid level:     "I'm making pasta with tomato sauce and a side salad."
Low level:     "Boil 4 quarts of water, add 1 tablespoon salt, cook 12 oz
               spaghetti for 9 minutes, drain, reserve 1 cup pasta water..."

A dinner guest needs the high level. Someone helping in the kitchen needs the mid level. Someone following the recipe for the first time needs the low level.

Travel

High level:    "I'm going to Japan next month."
Mid level:     "Flying into Tokyo, spending 4 days there, then taking the
               bullet train to Kyoto for 3 days."
Low level:     "Flight AA 175 departs LAX at 11:45 AM, arrives NRT at 3:20 PM
               next day. Hotel check-in at 4 PM. Subway from Narita to
               Shinjuku takes 80 minutes on the Narita Express..."

Education

A biology curriculum moves through levels of abstraction:

Elementary:    "Plants need sunlight, water, and soil to grow."
High school:   "Plants convert CO2 and water into glucose through
               photosynthesis using chlorophyll."
University:    "In the Calvin cycle, RuBisCO catalyzes the fixation of CO2
               into 3-phosphoglycerate, which is then reduced to G3P
               using ATP and NADPH from the light reactions..."

Each level builds on the previous one. You do not start with the Calvin cycle in third grade.

Levels of Abstraction in Technology

High-Level Architecture vs Low-Level Implementation

A software system can be described at many levels:

Highest:   "An e-commerce platform where people buy things online."

High:      "A web application with a product catalog, shopping cart,
           payment processing, and order management."

Mid:       "A React frontend calling a REST API backed by a PostgreSQL
           database, with Stripe for payments."

Low:       "The checkout function validates the cart contents, calculates
           tax using the TaxJar API, creates a Stripe payment intent,
           and inserts an order record with status 'pending'."

Lowest:    The actual source code, line by line.

Architects work at the high and mid levels. Engineers implementing features work at the low level. During code review, they move between levels constantly.

The OSI Model

Computer networking is organized into seven layers of abstraction, known as the OSI (Open Systems Interconnection) model:

Layer 7 - Application     What the user interacts with (web browser, email)
Layer 6 - Presentation    Data formatting and encryption
Layer 5 - Session         Managing connections between applications
Layer 4 - Transport       Reliable delivery of data (TCP/UDP)
Layer 3 - Network         Routing data across networks (IP addresses)
Layer 2 - Data Link       Communication between directly connected devices
Layer 1 - Physical        Electrical signals on cables, radio waves

Each layer only communicates with the layers directly above and below it. When you load a web page, your browser operates at Layer 7. It does not think about electrical signals. The cable carrying data operates at Layer 1. It does not know what a web page is.

This layered design allows each layer to be developed, improved, and replaced independently. You can switch from a wired connection to Wi-Fi (changing Layer 1 and 2) without changing your web browser (Layer 7).

File Systems

Your computer's file system works at multiple levels:

User level:      You see folders and files with names like "Budget.xlsx"
OS level:        The operating system sees file metadata, permissions,
                 and pointers to disk locations
Disk level:      The hard drive sees blocks of binary data at physical
                 addresses

You never need to think about disk blocks when saving a file. The file system abstraction handles that for you.

Moving Between Levels

The ability to move between levels of abstraction — zooming in and zooming out — is one of the most valuable thinking skills you can develop.

Zooming out means stepping back to see the bigger picture. It helps when you are lost in details and need to remember the goal.

Zooming in means diving into specifics. It helps when a high-level plan is not working and you need to understand why.

Good problem-solvers do this naturally. A doctor starts at a high level ("the patient has chest pain"), zooms in to investigate ("let's check the EKG and blood work"), and zooms back out to make a diagnosis ("this pattern suggests a cardiac event, not a muscle strain").

Common Pitfalls

Getting stuck at one level

People tend to be most comfortable at one level of abstraction. Engineers sometimes get lost in implementation details and lose sight of the user's actual problem. Executives sometimes stay at such a high level that their plans are not actionable. Practice moving between levels deliberately.

Skipping levels

Jumping from the highest level to the lowest level — or vice versa — without passing through the middle creates confusion. If a CEO asks about revenue and an engineer starts explaining database queries, several levels have been skipped. Build a bridge through the intermediate levels.

Mixing levels in the same conversation

When a discussion bounces between levels without acknowledging the shifts, people talk past each other. "Are we discussing the product strategy or the API design?" is a question that clarifies which level the conversation should be at.

Assuming everyone shares your level

What is obvious to you at your level of abstraction is not obvious to someone at a different level. A network engineer who says "it's a DNS issue" may need to translate that to "the system that converts website names into addresses is not working" for a non-technical audience.

Key Takeaways

  • The same thing can be viewed at many levels of abstraction, from very high (big picture) to very low (fine detail).
  • The right level depends on your role, your purpose, and the decisions you need to make.
  • Moving between levels — zooming in and zooming out — is a critical thinking skill.
  • In everyday life, levels of abstraction show up in cooking, travel, education, and virtually every domain.
  • In technology, systems like the OSI model, software architecture layers, and file systems are explicitly organized into levels of abstraction.
  • Effective communication requires matching the level of abstraction to your audience.