That hole on your laptop is actually a Kensington lock

Take a close look at the edges of your computer. You will probably notice a tiny rectangular hole. You may have observed it in the past, but never given it much thought. It doesn't look like a port, and even if you tried, you would not be able to get your commonly used peripheral devices to fit into it.

It's called a Kensington Security Slot and is included on about 95% of laptops. Primarily designed to attach a physical anti-theft lock, the Kensington Security Slot isn't like other laptop protections like encrypted drives and secure logins — this is designed to stop someone actually stealing your laptop when you're not around.

That tiny rectangle isn’t decorative

It’s the anchor point for one of the longest-running laptop security standards

The Kensington Security Slot is sometimes referred to as a K-Slot and allows you to secure a laptop physically to something that doesn't move.

The Kensington Security Slot was first created in 1992. The first-ever lock was the MicroSaver, created around the time laptops started becoming common enough to go missing from offices. The goal was to ensure your laptop doesn't walk away when you step out for five minutes. This was a low-tech but efficient solution that included a reinforced slot introduced into the chassis and a lock that anchors to it.

It was very innovative and quickly became one of the most universal hardware features of laptops. Adoption spread beyond laptops, and slots are typically included in many of the following devices:

• External monitors
• Docking stations
• Projectors
• Small form-factor desktop PCs
• Network equipment used in offices and schools

So, if you walk into a store and wonder why the laptop on the table can't be easily lifted, it's usually because a cable has been attached to the K-Slot.

The lock itself is surprisingly simple

A rotating latch and a steel cable are all it takes

This anti-theft lock plays a key role, yet it's mechanically very simple, consisting of just three parts:

• A lock head that inserts into the slot
• A steel cable
• A key or combination mechanism

First, you slide the metal head into the K-slot. Turning the key or combination mechanism spins the T-bar latch embedded in the device and catches it against the chassis' reinforced interior. At this point, the lock can't simply be pulled out, and all you have to do is loop the steel cable around something that isn't easily moved — a desk leg, table frame, or desk anchor may suffice.

The only option a bad actor has is cutting through the steel cable or unlocking it. However, Kensington locks are not indestructible. If a thief has enough time and a bolt cutter, they'll still make off with the laptop. This mechanism, however, simply serves as a deterrent.

The principle is similar to bicycle locks, which makes it inconvenient for thieves to move them. It's not necessarily an unbreakable system.

Not every “Kensington slot” is actually the same

Buying the wrong laptop lock is a surprisingly common mistake

Kensington slots are typically rectangular, but they do not always have the same dimensions. Smaller dimensions have been introduced over the years as devices have generally started becoming more compact. But here are the most common today:

The 3 x 7mm standard K-Slot was the original design and remains the most commonly supported anti-theft slot. It's probably the version you have if you use a traditional business laptop.

The Nano Security Slot is a more current design of the K-Slot. It was introduced as manufacturers made laptops thinner and needed a smaller opening that wouldn’t weaken the chassis.

Noble Wedge slots have a wedge-shaped design and are typically used in some Dell laptops. These locks are different and do not work with the regular lock heads.

It's important to know the variety in design because laptop locks are not always interchangeable. One that works for the standard K-Slot will not fit a Nano Security Slot or Noble Wedge Slot.

The strange reason most people never use it

A security feature that survived decades, even though owners ignore it

These slots are very common, but that doesn't necessarily make laptop locks common. In fact, most people never use a lock. A major reason is that manufacturers hardly include locks with laptops. So even though there is a slot, you will have to purchase a lock separately.

Also, the way people use laptops has evolved over the years. Today, laptops rarely leave home offices or living rooms, and in these places, theft is not a huge concern. Slots are a handy inclusion in places where laptops still move around a lot. These may include:

• Corporate offices with shared desks
• Universities and libraries
• Conference venues
• Coworking spaces

Business models like ThinkPads or HP EliteBooks and other enterprise-focused laptops still include K-Slots. They are often used in environments where you expect laptops to remain unattended. In electronics stores, laptops aren’t simply left unattended. They are fastened using a Kensington lock.

Some premium ultra-slim designs omit the security slot. This forces companies that need physical security to employ clamp-style laptop locks, adhesive anchor plates, or locking docking stations.

Note that in addition to protecting the hardware, I also encrypt my device to keep my data protected.

Now that you know what it is, check your laptop

You now know what the K-slot is. You may not have one on your laptop, but if you do, and you work from a coworking space or some other place where your computer may sit unattended, get a lock.

This is a security measure for hardware. If you work with public computers, consider securing the computer with certain portable tools before using it to keep your sensitive data safe.