Most guests have some idea of what's appropriate to wear to a wedding. Still, others don't. And while a Google search might teach them something about common dress codes, it won't tell them which one you're going with for your big day. Besides, what happens if you go a less traditional route, like asking everyone to outfit themselves in specific colors for a picture-perfect palette? To avoid confusion, it's best to make your attendees aware of your exact expectations.
If your dress code is simple and easy to understand (black-tie, for example), feel free to note it on your wedding invitation. If you want to provide a detailed explanation (not everyone is familiar with fashion etiquette), you can write up a blurb and stick it on an insert in your stationery suite.
But what if you don't want to take up space on your paper goods, or have a dress code that's complicated and could use some clarification? In this case, we recommend putting the information on your wedding website. It'll be easily accessible to everyone who has the link, and you'll have as much room as you need to describe the look you're hoping for. You can even include photo examples. Best of all, your attendees will be able to check back as often as they like to consult the dress code while they're planning their ensembles.
For the older folks on your guest list—or for anyone you worry might not visit your website—you can always supplement your online post by contacting those people a different way, like by phone.