Last year, on the fiftieth anniversary of restaurant desegregation, we celebrated a signifying moment in the long march toward full and equal citizenship for black Americans. But we delude ourselves if we don’t acknowledge that there is a difference between being admitted and being welcomed.

The court order that ended desegregation stipulated that every cafe, tavern, Waffle House, and roadside joint must open its doors to all. It did not, could not, stipulate that whites in the South must also open their hearts and minds to all. Welcome was, and is, the final barrier to racial parity.

We have witnessed remarkable progress over the past five decades, yes, and we should acknowledge this, too. What seemed fanciful, even utopian, a generation ago is now so commonplace as to not bear any comment at all. We have come to expect and accept black and white in the workplace, on the playing field, in politics, in the military, and we congratulate ourselves on our steady march to racial harmony. But our neighborhoods and our restaurants do not look much different today than they did fifty years ago. That Kingly vision of sitting down at the same table together and breaking bread is as smudgy as it’s ever been.

Todd Kliman set out to try to understand why, decades after desegregation, so few restaurants host a mixed clientele of black and white. Of course, the issues is about more than just restaurants. The questions he asks and the theories he uncovers can be pointed at bars, clubs, neighborhoods, and schools.

It was a man named Andy Shallal who helped me to understand the possibilities for a better, more integrated future while also reinforcing the manifold problems of the present. Shallal made me understand that no one ever need say, “keep out.” That a message is embedded in the room, in the menu, in the plates and silverware, in the music, in the color scheme. That a restaurant is a network of codes. It’s a phrase that, yes, has all sorts of overtones and undertones, still, in the South. I’m using it, here, in the semiotic sense—the communication by signs and symbols and patterns.

I don’t see coding as inherently malicious. But we need to remember that restaurants have long existed to perpetuate a class of insiders and a class of outsiders, the better to cultivate an air of desirability. Tablecloths, waiters in jackets and ties, soft music—these are all forms of code. They all send a very specific, clear message. That is, they communicate without words (and so without incurring a legal risk or inviting criticism or censure from the public) the policy, the philosophy, the aim of the establishment.

Today, there are many more forms of code than the old codes of the aristocracy. Bass-thumping music. Cement floors and lights dangling from the ceiling. Tattooed cooks. But these are still forms of code. They simultaneously send an unmistakable signal to the target audience and repel all those who fall outside that desired group.

The same codes are at work in websites and applications, though they often act subconsciously. Color, typography, imagery, layout, and so many other aspects of the user experience make different users feel more welcome than others.

Is your service more welcoming to the old or the young? Women or men? One ethnicity or another? The rich or the poor? The tech savvy or those less so? Those with fast internet access or those without? The visually inclined or the more textually focused? To new users or longtime users? The famous or the not-so-famous? Content creators or consumers?

It's rare the service that is perfectly neutral.