Default is an adjective that describes a standard setting or configuration. While it is not specific to computers, it is commonly used in IT terminology. In computing, "default" may describe several things, including hardware, software, and network configurations.
A default hardware configuration (or "default config") is a prebuilt system with standard specifications. This includes standard components such as the CPU, RAM, storage device, and video card. Retail stores typically carry default hardware configurations, while online stores are more likely to offer customization options.
In software, "default" describes preset settings. For example, when you install a program for the first time, it will load the default preferences. If you want to change these settings, you can open the "Preferences" window and modify the default options to suit your needs. Your web browser, for instance, might open new pages in tabs by default. If you prefer windows instead of tabs, you can change the default selection in the Preferences window. Some applications offer a "Restore Default Settings" command that allows you to revert to the original settings at any time.
In networking, "default" is often used in reference to protocols. For example, a web server may serve webpages over HTTP by default, but it may also offer a secure HTTPS option. Common protocols, such as FTP and SMTP are typically assigned default port numbers, but they can be altered for security reasons.
NOTE: While default is most often used as an adjective, it can also be used as a verb. For example, when a certain option is not available (such as a specific font), a program may "default" to the preset setting.