Getting beyond generalities about home and office MFPs, it's useful to make a list of the functions and features you actually need. Printing and copying are a given, and scanning is almost always included as well, but even these basics aren't as straightforward as you might expect. In addition to printing from and scanning to a computer, many AIOs today can print from and scan to cloud services, which can be useful for printing files already stored online, or for storing scans where you can download the files to any device that can connect to the service. If there's a particular online service you want to use, check that it's on the list that the AIO supports. Most AIO manufacturers also offer free apps that let you print from and scan to mobile devices, either by connecting your phone or tablet to the AIO directly using Wi-Fi Direct (sometimes hiding under a different name) or by connecting through Wi-Fi to the same network the AIO is on. You'll want to make sure the mobile printing and scanning works with the connection you plan to use. Similarly, if you plan to connect over a network, make sure the scanning works on a network. A few MFPs are limited to scanning over a USB connection only. Some AIOs rely on a computer for copying. If you want to copy with the computer off, be sure to pick one that works as a standalone copier, operated from its control panel. Much the same comment applies to faxing, but in reverse. Fax features almost always include standalone faxing, controlled through a front-panel keypad or touch screen. But they don't necessarily include a PC-controlled faxing function, which would let you fax documents directly from your PC without having to print them out first. PC faxing can be in the form of a fax utility, a fax driver that you use like a print driver, or both. There's another twist to look for in fax features. Until recently, faxing by AIO required a connection to a phone line. In most cases it still does, but a few AIOs now offer faxing through the cloud. The cloud service connects to the telephone network to send and receive faxes, and provides you a phone number for receiving them. The cost for the service can be lower than the cost of maintaining a separate fax phone line. Email features also come in two forms. A direct-email function (mostly useful in business environs) lets you scan a document and send it as an email attachment directly to your internet service provider (ISP) or an in-house email server on your network. The more common choice for low-end AIOs is to open an email message on a PC and add the scanned document as an attachment. Any given AIO can offer either or both kinds of email. Note that some direct-email features won't work with all ISPs, so be sure to find out if they will work with yours before buying. Almost all AIO printers include flatbeds suitable for scanning photos or single-sheet documents. An automatic document feeder (ADF) will let you easily scan (plus copy, fax, and email) multipage documents. For models that have letter-size flatbed platens, an ADF will often let you scan legal-size pages as well. But not all do, so check first. Some ADFs can also perform duplex scans (that is, they can scan both sides of a page). The duplexing can be fully automatic, or it can be done through firmware or a computer app that will let you scan one side of a stack of pages, turn the stack over to scan the second side, then automatically interfile the pages in the right order. If you have to deal with multi-page, two-sided documents, some variation of this feature is all but essential. The fastest, most convenient, and most expensive choice for scanning two-sided pages is an ADF with one-pass scanning—meaning it can scan both sides of each page at once. Second best, and the approach offered by most duplexing ADFs, is to scan one side of each sheet, turn it over automatically, and then scan the other side before feeding the next. The semi-automatic option, with you having to re-feed the stack, being careful to feed it in the right orientation, is the solid third-place choice. However, many ADFs don't offer even that feature, and if you deal with duplex multi-page documents at all, it's a lot better than having to feed and refeed every page individually. One other important item to check is whether the ADF's duplexing feature works with all functions that use the scanner: scanning, copying, and faxing. (Some don't.) Note that for AIO printers that offer some variation of duplex scanning along with duplex printing, you can usually copy both single- and double-sided originals to your choice of single- or double-sided copies. For those that offer print duplexing only, some will still give you the choice of copying single-sided originals to either single- or double-sided copies.