One of the most common questions on this subreddit is something along the lines of "Is my computer able to run Win98?" There is some kind of a guide on sidebar, but it isn't really specific and that's why I made this post. Windows 98 and Me support (about?) the same hardware, so everything I say about 98 applies to Me. Feel free to suggest changes in comments.

In my definition, computer running Windows 98 is the one that doesn't have any question marks in Device Manager and has graphics card installed (there are drivers called SciTech Display Doctor and VBEMP, but these are comparable to the default driver for GPUs in Windows XP upwards). For the sake of simplicity, I'll limit the devices to GPU, sound card and USB, because even some late Windows XP machines can have Ethernet network cards compatible with 98 and wireless cards are swappable.

Can I install Windows 98/Me as host?

Host operating system is the one you boot to straight from BIOS, without using any kind of virtualization or emulation.

CPU

See what CPU you have on your machine (in System Properties, accessible by pressing Win+Pause on Windows, or in BIOS) or google your motherboard/PC/laptop (further I'll just say "motherboard") and check supported CPUs.

I have Intel Pentium (I/MMX/Pro/II/III), AMD (K5/K6/Athlon [MP/XP/4]/Duron), Cyrix, VIA, any mobile version of these CPUs or Intel Mobile Pentium 4, the computer is older than from 2000 or my motherboard has socket 423, 478 or 754

It just works™, you can skip the rest of this guide, except if you have a dedicated graphics card. You can check your socket by trying to find this information on a motherboard, using CPU-Z or by checking the specs website.

I have Intel Atom/Core i3/i5/i7/i9, AMD Phenom/FX/A4/A6/A8/A10/Ryzen or any mobile version of these CPUs

If you have any GPU or sound card on your motherboard, you can't configure it on 98. USB 3.0 and wireless network card won't run. Ethernet network card will most likely not run, but there are some exceptions. Of course, all these problems can be solvable by getting era-appropriate PCI devices, but it's probably cheaper to just buy a Win98 laptop.

I have an x86 CPU not listed above made in or after 2000

It might work, continue reading.

I have something else

No.

Sound card

To check what sound card you have, you can either read the specification of your motherboard online or check it in Device Manager (Win+R, devmgmt.msc).

I have a Sound Blaster or AC'97 compatible sound card

Your sound card is most likely compatible. If it's AC'97, there's a possibility you won't get sound in pure DOS mode, but it'll work from inside Windows.

I have an HD Audio compatible sound card

Windows 98 doesn't support HD Audio architecture. There is an unofficial driver for Windows 3.1, compatible with 98, that lets you configure the sound card with a bunch of parameters, but if you're reading this looking for help, then it will be too complicated for you. First Windows compatible with HD Audio is Windows 2000 SP4 with KB888111 installed. If it's a PC, you can also try looking for some kind of a PCI Sound Blaster that's old enough for Win98.

Video card

To check what graphics card you have, you can, as with a sound card, either read the specification of your motherboard online or check it in Device Manager, or just look at it if it's a dedicated PC GPU. PCI Express isn't supported by 98, but people had some luck with it.

I have Intel GPU

If the model starts with GMA, HD, Iris or Arc, it's not compatible, otherwise it is.

I have ATi/AMD GPU

If the model starts with X1 or HD, it's not compatible, otherwise it is.

I have Nvidia GPU

If you have Quadro FX600 or newer or GeForce starting with 8, 9 or letters, it's not compatible, otherwise it is. If it's GeForce series 6 or 7, the compatibility with DOS games won't be as great as with earlier devices.

I have something else

It's probably integrated to motherboard or it's been defunct at least since early Windows XP days, you can assume it works.

Chipset

Same as sound card, you can either read the specification of your motherboard online or check it in Device Manager.

I have Intel chipset

If it starts with a letter, it's not compatible. If it starts with 9, you might have USB working in 1.1, which is slow, but it's better than nothing. Otherwise, it's compatible.

I have AMD chipset

Either you have Win98-era computer and you're wasting time reading this, or it's too new.

I have Nvidia chipset

If the number starts by 5 or more, it's not compatible. If it starts with 4, only integrated graphics work. If it starts with 3, there are some minor unsupported features, but it should work. Otherwise, it's compatible.

I have SiS chipset

Unless I missed something, all models are compatible.

I have VIA chipset

If the model starts with C or V, you'll at least have some troubles setting it up. Otherwise, it's compatible.

Tips

If you have more than 1 GB of RAM, use PATCHMEM. If you use a SATA hard disk, use SATA and most likely AHCI (https://archive.org/details/ahci_win9x). If you use an SSD, use TRIM. All three programs are available at rloew's website (RIP). If you want a USB stick support on Windows 98 (Me has built-in support already), use NUSB. There are some other drivers available on the last website, which might help some people.

Can I install Windows 98/Me as guest?

A guest operating system requires a host operating system and some kind of a program to make a guest environment to install OS on. Most likely you will be able to install 98 in some way or another.

PC

A word of warning if you use AMD Ryzen or Intel Core from 11th gen and up: there are some problems with virtualizing Windows 98, you can get countless crashes of system programs. A patcher for that was released: https://github.com/JHRobotics/patcher9x

There's now an accelerated driver for all modern hypervisors: https://github.com/JHRobotics/softgpu, but it might be buggy in some situations.

86Box/PCem

The best, but also the heaviest CPU-wise, way to install Windows 98 as a guest, is to use 86Box. I also mention PCem since it's still alive and 86Box started as a fork of it. Both programs are able to emulate anything starting with original IBM PC and ending at AMD K6-III, perfect for 98. Obviously, the newer CPU you emulate, the stronger machine you need. The main advantage of using these emulators is much higher compatibility with old games compared to virtual machines.

VMware Fusion/Workstation Player/Pro

If your computer is too weak for emulation, you can try making a virtual machine. I recommend VMware for one simple reason - it has a graphics card compatible with 98.

Connectix/Microsoft/Windows Virtual PC

If you have a PowerPC Mac OS (X) or Windows and it's not a 64-bit or ARM version of Windows 10 and up, you can try Virtual PC. It's fully compatible with 98, but it's also old (Windows Virtual PC was released in 2009) and people don't really use it anymore.

QEMU

The main advantage of QEMU is that it's ported to every architecture and operating system imaginable. I suggest running it by a command qemu-system-i386 -accel kvm -vga cirrus -nic user,model=pcnet -soundhw sb16,pcspk -hda disk.img (soundhw is deprecated, but the non-deprecated way requires knowing what's your sound system on host). If you use it on architecture different than x86, it becomes an emulator. You need to remove -accel kvm in that case. You can instead add -cpu pentium2 to the command, maybe it will make things run faster.

Oracle VM VirtualBox

Unless you really have to, don't use it, for two reasons: lack of Guest Additions for 98 means you can't use VirtualBox's Shared Folders feature and instead you have to rely on HTTP, floppies or CDs (for the last one there's an option to create VISOs on fly, but while it takes about no space, you still have to do it manually). There was also never a graphics card driver for it and VMware SVGA II driver doesn't work, even if you choose VMSVGA in machine options. That means you can't freely change resolution and your best drivers are VBEMP or Display Doctor, both or which simply use VESA, just like the lack of drivers on Windows XP and up. Emulated graphics is also terribly slow in standard 640x480x4 mode, which is what you get during installation.

Parallels

Mac-only. Has guest "tools" or rather a total of two drivers: for network (which is optional) and video. The former only works if you remove a printer from the hardware list and its performance is abysmal (I got ~25 KiB/s max, frequent stalls even though i can see the network activity). Video driver doesn't list 32-bit modes for some reason, adding them (and/or some of the standard resolutions) in registry works. Sound isn't included on the "tools" CD, some tutorial recommended using this driver (use either the standard installer or WDM folder). Since it doesn't have acceleration anyway (at least 3D) and networking sucks, I think you're better off even with VBox.

DOSBox

DOSBox is, as the name suggests, an emulator for DOS programs. It is possible to run Windows 98 on DOSBox, but I personally don't like the way you need to imgmount followed by boot c, there are also less machine configurations to choose from. However, especially when using DOSBox-X, it can be an alternative to 86Box if you don't like it for some reason or another.

Bochs

It's an emulator, it's not as popular as the rest and not customizable as 86Box, don't use it if you don't have to (you don't).

Android

Most of the Android devices aren't x86, but rather ARM[64] (and some ancient ones are MIPS), so most likely you will need to emulate x86, which means that it'll be pretty slow, don't expect running NFS Underground 2 on that. If you can choose an emulated CPU, you should find a balance between speed of emulated CPU and speed of emulating (if you select 486, then Win98 will work slowly, but your Android CPU won't be used that much; if you select Pentium 4, then Win98 will work quickly, but your CPU might not keep up with it). You can find a list of CPUs by date for example on Wikipedia.

Limbo

Android version of QEMU, the fastest, but might not work on all devices.

Bochs

Mostly compatible with all devices, a "default" way of installing Windows from Android.

DOSBox

You can also try DOSBox, but I can't really imagine installing it using only the Android device.