What exactly does Cisco systems do?

I’ve read the home page of Cisco Systems . It looks like the company sells physical products which are used by large companies to work with their computer systems. Is this correct?

Why was this company considered the most important in the United States during the dot com era?

They manufacture network routers which are at the heart of many of the world’s largest and most complicated IP networks.

They also own Linksys, the largest manufacturer of small network routers.

Cisco makes the fittings that connects tubes to other tubes.

Cisco is a massive company that offers a broad selection of hardware products, software, and services.

As friedo mentioned, their primary product line is routers and switches. Pretty much anything relating to moving bits around on a network. When I worked there, they had more people writing software than they did designing hardware, but most of the software was for their own proprietary products.

As for the second question, they company was at the core of the dot-com boom because most dot-com companies used (and still use) Cisco products at the cores of their networks.

Cisco, and companies like it, make the hardware and software that physically routes and sends data through computer networks (like the internet).

They also sell VOIP telephony systems, mostly for mid-sized and large corporations. And they recently introduced a fancy, elaborate videoconferencing system. Basically, though, all the products other than routers or switches are designed to increase the amount of IP traffic, so that its customers will need bigger and faster routers and switches.

They were certainly one of the most important companies (and still are) but I’m not sure I’d call them the most important, or even at the core. They got hurt also by the crash - they wrote off an incredible amount of inventory, in the billion dollar range IIRC. But plenty of other companies are as important or as big - HP, Intel, Microsoft, IBM, Sun, Dell, in the supplier space.

A lot of people were making (and make) equivilent or better perfoming products than Cisco. But unless I am mistaken (I left the industry years ago) Cisco was really, really good at providing a common interface across all of their product lines, even outside designed stuff that they acquired via purchase. So installation, integration and maintenance routines for all of their various products would follow the same pattern, same procedures, use the same terms and nomenclature and so on. The screen for administrating one Cisco product would be almost identical for any other Cisco product. This is what Cisco did more than anyone, and it was one of the primary reasons for its success.

It helps to have its own proprietary software, called Pancho.