Basic Anatomy of a Backpack

Despite the abundance of backpacking-specific terms and jargon, a backpack is a fairly utilitarian piece of gear—it’s designed to carry everything you need for a day, night, or even weeks in the woods. If you’re getting tripped up by complicated product descriptions and ever-evolving features, realize almost all backpacks share the same foundational parts. With this in mind, here’s the basic anatomy of a backpack. 

• Top Loaders vs. Panel Loaders
• External Frame, Internal Frame, and Frameless 
• Suspension System
• Other Common Backpack Parts

Top Loaders vs. Panel Loaders 

One of the most noticeable distinctions between backpacks is how you access their main compartment, which is typically through the top (top loading), the front (panel loading), or a combination of the two. 

Top loading: As the name implies, the main compartment of a top-loading backpack is accessed from the top. It’s common for a lid or “brain” to cover a drawstring closure on top-loaders, but roll-tops and zippered clamshell closures are also popular. 

Panel loading: Most commonly found on the front of a pack, panel loaders allow users to access the inside via a zippered panel which exposes the entire interior of the pack. 

Best of both worlds: Many backpacks, particularly those designed for spending multiple days in the backcountry, feature a variety of access points including both top and front, along with side and bottom. 

External Frame, Internal Frame, and Frameless 

The frame of a backpack both gives it shape and helps support loads. The majority of the packs you see today have internal frames; however, external and frameless packs still have their place. 

Internal frame packs: The advent of sleeker, lightweight outdoor gear has made internal frames the most popular style of pack. Features like stable load carrying and sitting flush against your back make them a favorite of those traveling on uneven terrain. 

External frame packs: These packs are excellent for carrying heavier loads and awkwardly shaped items. The downside of external frame packs is that they’re typically heavier themselves and are less maneuverable than other types of packs. 

Frameless packs: Forgoing the comfort and stability of a frame to save weight, frameless packs are the go-to option for ultralight backpackers who prioritize speed over comfort. 

Suspension System

The workhorse of a backpack is its suspension system, which is responsible for safely and comfortably distributing the weight of the pack to your back. The suspension system consists of a combination of parts working unison and includes:

• Shoulder straps: preferably padded, shaped to your body, and breathable 
• Hip belts: also commonly padded (some packs favor weight savings over comfort), breathable, and adjustable 
• Load lifters: straps that attach the shoulder straps to the pack frame and allow you to adjust the weight of the pack between your shoulders and hips
• Back panels: designed for comfort and support—some are highly padded while others favor structures that enable airflow 

Sternum strap: connects the two shoulder straps to keep the pack from shifting while on the move 

Other Common Backpack Parts 

Although the building blocks of a backpack consist of its access, frame, and suspension, there are a handful of other features commonly found on them, including: 

• Water bottle pockets for getting a drink on the go 
• Hydration sleeves for those who want to use a reservoir rather than a water bottle 
• Hip belt pockets for keeping snacks and small accessories easily accessible 
• Front/Kangaroo pockets located on the front of the pack, handy for storing everything from lightweight jackets to maps 
• Attachment points dedicated to securing items like ice axes and trekking poles

Although every pack manufacturer has unique designs and features that differentiate them, and shopping for a backpack can feel daunting, just remember that even though not all packs are created equally, they do all share a similar basic anatomy.