What would Facebook look like without photos of drunken nights out and tales of misbehaving cats? It might look a lot like the internal social network at the offices of Nikon Instruments.

The tone is decidedly businesslike, as employees exchange messages about customer orders, new products and closing deals. And the general rule is that “if you don’t want your company president to see it, don’t post it,” said John G. Bivona, a customer relationship manager at Nikon Instruments, which makes microscopes.

As social networks increasingly dominate communications in private lives, businesses of all sizes — from tiny start-ups to midsize companies like Nikon to behemoths like Dell — are adopting them for the workplace. Although it is difficult to quantify how many companies use internal social networks, a number of corporate software companies have sensed the opportunity and are offering various systems, some free to existing customers and some charge a minimum fee per user.

Its one more instance of how consumer technology trends, like the use of tablet computers, are crossing into office life. Because of Facebook, most people are already comfortable with the idea of “following” their colleagues. But in the business world, the connections are between colleagues are meant to be about work matters — like team projects, production flaws and other routine business issues.

At Nikon, for example, which employs 500 people in offices throughout the US, Canada and Brazil, a code of conduct for using the service leaves little room for the idle chit-chat that is pervasive on Facebook. Still, it can be tricky to transport the mores and practices of social networking into the office.

For instance, some workers prefer to be “lurkers” who read posts rather than write them. Others are just not interested. At Symantec, the computer security company, a few employees initially disliked the idea of an internal social network but nevertheless used it to air their complaints.

Another issue is how to protect corporate secrets. The systems are generally set up so that companies can determine who sees particular files and who belongs to specific groups on the network. Companies that provide social networks respond to concerns by emphasising their rigorous security. Still, some offer networks that allow customers to keep their data on their own servers.

One of the biggest providers of corporate social networks is Salesforce.com, the online business software company based in San Francisco. It said 80,000 companies use its corporate social network, Chatter, up from around 10,000 when it was introduced a year ago. Yammer, a start-up and also based in San Francisco, said its service is used by more than 100,000 companies, up from around 80,000 a year ago.

SAP, Cisco Systems, Socialtext, Jive Software and SuccessFactors are also pushing their products. Last month, VMware joined the list when it acquired Socialcast, one of the earlier networking services.

Salesforce and Yammer both offer free versions of their social networks to companies. Salesforce charges $15 per user a month for its premium network — existing software customers pay nothing extra, however — while Yammer’s costs $5 per user a month.

At Symantec, which is based in Mountain View, California, more than a third of the 18,500 employees are able to use Chatter. More employees, and potentially some of the company’s partners, will be added to the network later this summer.

Still, Troy McKaskle, a chief technology officer at Symantec, is an evangelist for Chatter, which he says helps employees with everything from getting advice about how to configure their iPads to getting feedback on projects.

McKaskle follows around a dozen groups on the service and posts messages frequently. On a recent day, he wrote, “Get ready for Odyssey!” using a code name for a new technology Symantec is developing.

“Dare I ask what Odyssey is?” a colleague responded.

Keeping posts relevant is important to the success of social networking within companies, managers of the networks agree. “White noise” will only annoy people and cause them to ignore the services.

One of the benefits of social networks for many employees is a decline in email use. Instead of sending out mass mailings, workers post messages or collaborate on presentations within the service.

Scott Lake, director of VIP marketing at Caesars Entertainment, the casino colossus based in Las Vegas, said his team used Chatter to coordinate and promote events like Celine Dion concerts for the casino’s best customers. Online groups set up for each event help ensure that everyone involved has the most up-to-date information.

Questions and answers are visible to everyone in the group. Doing the same thing via email would be cumbersome if not impossible.

“Before, we got on conference calls and hoped the information would be passed around,” Lake said. “Now, we have a lot fewer calls and meetings.”