The Web has made it possible for anyone to find others who share their interests. You’ll recognize what a great thing this is if you had offbeat interests as a kid, before the web came into existence. Even if you’re homebound, you can participate in a circle (or multiple circles) of interaction, ranging from online literary and political discussions to scrabble, chess, and other games, to sharing recipes and knitting or quilting techniques.
In addition, the Web is a gateway to face-to-face interactions. Although many Americans live in communities where they don’t know their near neighbors, Meet-up groups exist in most cities of any size that bring together individuals who find each other on the web through their shared interests.
The need for safe and appealing places where older people can meet and socialize has been recognized and efforts are being made to address it. Senior Centers, created under the Older Americans Act and traditionally used mainly by the poor, are being retooled as places for younger, healthier people to congregate (think yoga classes). (This can be taken to extremes as per this article about for-profit adult daycare centers using Medicare dollars to lure in rich people.)
In many cities, McDonald’s and Starbucks serve as gathering places for over-65 groups.