A Debian system can be installed from several types of media, as long as the BIOS/UEFI (see
笔记 UEFI，一个 BIOS 的现代替代品) of the machine allows it. You can for instance boot with a CD-ROM, a USB key, or even through a network.
最常见的安装介质是CD-ROM（或者DVD-ROM）：计算机从此处引导，然后安装程序接管。
Various CD-ROM families have different purposes: netinst (network installation) contains the installer and the base Debian system; all other programs are then downloaded. Its “image”, that is the ISO-9660 filesystem that contains the exact contents of the disk, takes up about 310 to 780 MB (depending on the architecture). On the other hand, the complete set offers all packages and allows for installation on a computer that has no Internet access; it requires around 21 DVD-ROMs (or 5 Blu-ray disks). There is no more official CD-ROMs set as they were really huge, rarely used and now most of the computers use DVD-ROMs as well as CD-ROMs. But the programs are divided among the disks according to their popularity and importance; the first disk will be sufficient for most installations, since it contains the most used software.
There is a last type of image, known as mini.iso, which is only available as a by-product of the installer. The image only contains the minimum required to configure the network and everything else is downloaded (including parts of the installer itself, which is why those images tend to break when a new version of the installer is released). Those images are usually smaller than 100MB, and they can be found on the normal Debian mirrors under the dists/release/main/installer-arch/current/images/netboot/ directory.
To acquire Debian CD-ROM images, you may, of course, download them and burn them to disk. You may also purchase them, and, thus, provide the project with a little financial support. Check the website to see the list of DVD-ROM image vendors and download sites.
因为大多数计算机能够从 USB 设备启动，所以你也可以从 USB 盘（小闪存盘）安装 Debian。
安装指南说明了怎样做一个包含debian-installer的 USB 盘。安装过程很简单， 因为i386 和 amd64 架构的 ISO 镜像是混合（在一起）的， 从 USB 盘引导与从 CD 引导的镜像是一样的。
You must first identify the device name of the USB key (ex: /dev/sdb); the simplest means to do this is to check the messages issued by the kernel using the dmesg command. Then you must copy the previously downloaded ISO image (for example, debian-12.0.0-amd64-netinst.iso) with the command cat debian-12.0.0-amd64-netinst.iso >/dev/sdb; sync. This command requires administrator rights, since it accesses the USB key directly and blindly erases its content.
A more detailed explanation is available in the installation manual. Among other things, it describes an alternative method of preparing a USB key that is more complex, but that allows you to customize the installer's default options (those set in the kernel command line).
许多的 BIOS 允许从网络上下载内核和一个最小化的文件系统镜像并直接以此进行系统引导。这种方法（有几种不同的名称，比如
PXE 或者
TFTP 引导）在计算机没有光驱、或者 BIOS 无法从其它介质进行引导的时候就是最后的一条救命稻草了。
这种安装方法分两个步骤。第一步，在引导计算机时， BIOS（或者网卡）发出一个 BOOTP/DHCP 请求以自动获取 IP 地址。BOOTP 或 DHCP 服务器返回的响应将包含一个文件名以及当前网络的设定情况。在配置好网络后，客户端计算机发出一个 TFTP（简单文件传输协议）请求，所请求的文件名称由先前的响应决定。在文件获取完成后，它将作为一个引导程序被计算机执行。此后，它将会启动 Debian 安装程序，安装程序将正常运行，就好像它是从硬盘、CD-ROM 或是 U 盘引导运行那样。
所有该方法的细节都在安装指南里（“准备用于 TFTP 网络启动的文件”章节）。
When we have to deploy customized installations for a large number of computers, we generally choose an automated rather than a manual installation method. Depending on the situation and the complexity of the installations to be made, we can use FAI (Fully Automatic Installer, described in
第 12.3.1 节 “全自动安装器 （FAI）”), or even a customized installation DVD with so-called “preseeding“ (see
第 12.3.2 节 “预设值 Debian 安装”).
It should also be noted that the installer can load and run an SSH server and thus provides the ability to install Debian remotely via an SSH session. The release notes also describe how to run the installer from an existing system using grub to replace it completely.
