When you need to sign a document that's sent to you as a PDF or a Word file, you can easily take care of that using your phone. Whether you use an iPhone or an Android phone, both include built-in options for adding a quick signature onto a document, saving a new copy and sending it off to whomever you need.

These tools work in a pinch, but I wouldn't recommend them if you're marking up a more in-depth document that requires multiple signatures and filling out many text boxes. A more advanced signing tool like DocuSign or Microsoft 365 is better optimized, and frankly, if you're signing something like an apartment lease, you might want to break out a bigger screen like a computer or tablet.

Most documents that need your signature are much shorter and simpler, so if you're dealing with one of those, then Apple's Markup tool and the Google Drive app each include a quick way to get your documents filled out and on their way.

The Google Drive app -- included on all Android phones and can be downloaded onto an iPhone -- includes markup tools that make it easy to sign a document.

When using Google Drive on Android, you'll first need to open the PDF that you want to sign.

When it's open, depending on the file, you'll either get an Edit option marked with a pencil or an Annotate option marked by a pen with squiggly lines. If you have the Edit option, you can then select Form Filling to enter your additional information. If you have only the Annotate option, you can tap it to bring up a pen tool, and you can use that to give a quick signature to your document.