The first all-in-one PC I ever saw was a Compaq Presario CDS 520, but I expect most people's first contemporary experience with the "PC in a monitor" idea was with Apple's fruit-flavored iMac G3. Things have come a long way for the concept. For example, Apple's iMac Pro can house 18 CPU cores and Radeon Vega 64 graphics in a slim package. Folks who don't need all that hardware might prefer something a little simpler like Acer's Aspire S24. This svelte system boasts a 24" display just under six millimeters thick.
Unlike the iMac, the Aspire's guts rest in the base of the machine. Despite the box's small size, Acer packs in a Core i5-8250U quad-core Kaby Lake-R CPU that will turbo to 3.4 GHz. 12 GB of dual-channel DDR4 memory running at 2400 MT/s comes standard. Unfortunately, Acer elected to provide the machine with a 1-TB hard drive as its sole storage device, but at least you get plenty of space. Acer notes that it's a standard SATA drive, so you might be able to replace it for an SSD fairly easily.
Graphics duties are handled by the Intel UHD Graphics 620 built into the CPU. That should be plenty serviceable for the S24's 1920x1080 IPS display. Notably, said display has an extremely-slim 2.7-mm bezel on three sides. Acer says the monitor is free of PWM-induced flickering, too. If you must connect additional monitors, there's a pair of HDMI connections. Other external devices can hook up to a USB Type-C port, one of three USB 3.0 Type-A ports, or a single USB 2.0 port. Network connectivity comes in the form of 2x2 802.11ac Wi-Fi as well as Gigabit Ethernet. Finally, there's a headphone jack, but you don't necessarily have to use it because the Aspire S24 has "2.1" speakers built in.
The keyboard and mouse included with the machine are wireless. You can alternatively use Bluetooth to hook up your own input devices. In one of the more interesting features of Aspire S24, the base supports Qi wireless charging for compatible devices. That's pretty convenient, since the base presents a handy spot to drop your device when you sit in front of the PC. Acer says the Aspire S24 will be available in the US this month for $880 with a one-year warranty.