When you’re shopping for electronics, you might wonder what the numbers you see on different products mean. What does it mean if a smartphone has 4GB of RAM? What’s the difference between an 8MP camera and a 12MP camera? What is 4G LTE?

Understanding these kinds of numbers helps you make a better buying decision and pick out a product that meets your needs. Here’s a look at some of the tech specs you’re likely to encounter so you can make the best selection when you shop.

Processor Speed

The central processing unit (CPU) of a computer or smartphone chip is the brain of the device. Processors differ in speed, or clock rates. They are measured in Gigahertz (GHz), which represent billions of internal clock ticks per second. Processor speeds range from 1 to 3 GHz. Processor speed affects how fast your device can perform actions and has the biggest impact on your computation-heavy tasks, such as video editing or gaming.

Processors have cores that act independently. Today’s better smartphones have multiple processors with multiple cores, which affects their speed. For instance, the Samsung Galaxy S6 has an Exynos 7420 Octa-core 64-bit processor, which has eight cores.

Most processors are made by Intel or AMD. Samsung partner Qualcomm also makes its own cutting-edge processor, called the Snapdragon. Intel processors are categorized as i3, i5 and i7, with the higher numbers representing more cores. AMD processors have two, four, six or eight cores. For devices with Intel processors, look for a core of at least i3 or i5. For AMD-powered devices, look for at least dual core or quad core features. The Snapdragon 820, which is used in the Galaxy S7, is quad core.

Memory

Another number you should understand is how much RAM a device has. When you’re comparing devices, the more RAM you have, the smoother the device usage will be. This type of memory pulls information from the hard drive and is the amount of space you have to run programs. The more RAM you have, the more programs you can run at the same time.

For most computer users, 4 gigabytes (GB) of RAM is sufficient. If you’re a heavy gamer or need high-end graphics and resolution, you may need more RAM for your graphics card. For mobile devices, 2GB of RAM is the lower limit for running an Android device if you want to multitask. Four GB is about the upper limit for what you can use efficiently. Apple mobile devices need about 2GB of RAM to handle multitasking.

Operating System

Your operating system (OS) is the software that runs your computer as well as the programs your computer runs. The most common operating systems for computers are Windows for PCs, macOS (formerly OS X) for Macs and Linux for certain specialized applications. For smartphones, the most common operating systems are Android and iOS. Chromebooks run on Google’s Chrome OS.

New versions of operating systems are typically indicated by a number, such as Windows 10. Android uses candy-related terms for its naming convention, such as Lollipop, Marshmallow and Nougat. When choosing devices, look for the most current operating system for the type of device you want.

Camera Specs

Just as screen resolution is measured in pixels, camera picture resolution is measured in megapixels (MP), or millions of pixels. Current trends in smartphone cameras range from 8MP for the iPhone 6 to 16MP for the Galaxy S6. Keep in mind that your camera lens and light sensor also impact the quality of your picture, so more MP doesn’t automatically mean a better picture.

Phone and Internet Connectivity

Mobile devices typically list a number of different phone and Internet connectivity specs. Wi-Fi standards begin with an 802.11 prefix, which distinguishes them from other connectivity methods such as Bluetooth. This prefix is followed by letters to identify the different standards, such as 802.11ac.

Wireless communication is measured in kilobits per second (kbit/s), megabits per second (Mbit/s) or gigabits per second (Gbit/s). Standards include 3G (third generation), which supports at least 200 kbit/s; 4G (fourth generation), which is significantly faster with at least 100 Mbit/s for mobile users and 1 Gbit/s for stationary users; and 4G LTE (fourth generation long term evolution), which has transfer speeds of at least 300 Mbit/s for downloads and 75 Mbit/s for uploads.

Battery Life

A final spec to pay attention to is battery life. This is typically listed for both talk time and standby time. For instance, the Galaxy S6 lists a battery life of up to 20 hours of talk time and 12 days of standby time. Battery life listings represent manufacturer tests under ideal conditions rather than actual use.