LinkedIn has over 400 million users and is growing. Who would have thought that this business social networking site would keep growing at the rate it has, plus have such a positive effect on businesses worldwide? The average CEO has 930 connections on LinkedIn, which is incredible. Soon we'll all be within two degrees of connection to each other.

To answer the question "Does anyone know anyone at Widgets Inc.?" most people these days hop over to LinkedIn to to see if someone already in their network does, or to search and connect with someone else who does.

The number of users and their propensity to want to network is the main reason LinkedIn marketing should be important to you, especially if you're marketing to businesses. Here are three reasons why you need to have it on your radar in 2016.

1. Business still happens because people make it happen.

Business is still done by people making things happen, so it's important for you to connect and refer. You need to accept invitations from legitimate people who are reaching out to you. You need to answer back any emails (inMails) you get from people, even if it's a nice "no" to a solicitation. You need to search keywords for people you should get to know and reach out and connect with them. This is especially important if you're running a company, because your team members will look to you to make a connection happen.

For instance, at my startup Dasheroo, I needed to find contacts relevant to a few VCs. I realized after going to LinkedIn and searching the names of various companies that I was a second-degree connection to many people who worked at these firms. So I went ahead and asked them to connect. Almost all of them did. When it's the right time for me to connect, I'll at least have a potential open door to a conversation with them.

Eve Mayer, CEO of Social Media Delivered and the LinkedIn Queen, says, "Social media is connecting through new technologies in a way that enables communication and builds relationships." We couldn't agree more.

2. The power of LinkedIn groups.

The great thing about LinkedIn groups is that people have self-selected themselves (or have been invited) to be a part of a targeted community. And there are literally millions of them. The community is made up of people who like to share their content, get a job description out there (or look at some), and network with like-minded pros.

If that community is based around an industry you serve, you need to be a part of it.

It's simple: In LinkedIn's search bar, type in the keywords that match your industry. Then assess all of the groups that surface that you want to be a member of. It's important to make sure you fill out your LinkedIn profile and company profile as much as possible. LinkedIn will go ahead and recommend groups for you to join.

According to Viveka Von Rosen, author of LinkedIn Marketing: An Hour a Day, there have been recent changes to the LinkedIn Groups features. One of the most noticeable is that there are no more open groups, so you'll need to ask to join the standard group. There are unlisted groups as well, but you'll need to be invited to them.

"Although it will be more difficult to use groups for prospecting and lead generation," says Von Rosen, "people can still use groups for content marketing."

LinkedIn Groups

Now you'll be able to participate. When you do join a group, make sure you check on it every so often, participate in the discussion, and share updates you think the group might be interested in. This is free advertising, people! And when someone replies to your updates, make sure you acknowledge with his or her name in your own reply to clearly indicate that you've read what he or she said.

LinkedIn Group--Replies

You'll get yourself and your company known as industry experts and when they need what you offer, they'll think of you.

3. Free advertising for your content.

If you're producing content, LinkedIn is a great way to share and measure it. At Dasheroo, we repost our important blog posts in long form to LinkedIn and as soon as they're published we share them as an update on LinkedIn. This way we get "triple miles" -- posting it to our blog, then sharing the update, and then a few days later posting the long form to LinkedIn.

LinkedIn Long Form Content--Dasheroo

We also link to our other popular articles that we publish on the bottom of each long post so we can get more traffic back to the blog.

LinkedIn Groups

Finally, we share the long posts directly to groups we're members of.

The bottom line is that the more people in your LinkedIn network and the more visibility you get when you post or reach out for a favor or a connection,  your connections will remember you and lend a hand.