What systems for business do you know?

What systems for business do you know? When everyone has the Internet, smartphones, laptops, and doing business has become much easier. We have developed many programs that could successfully do business. Now we can communicate via the Internet, solve important cases and much more. Almost everything is translated into the electronic version. And however it's convenient. I am now considering different systems for business, so that you can create different projects and solve them together online. Well as to business matters and so on. I wanted to know what you know such systems for the convenience of doing business?