If you ask anyone under the age of 13 what the symbol "#" is, they'll unanimously say "hashtag." 10 years ago this week, the pound sign was officially rebranded as the hashtag, thanks to Twitter.

On Aug. 23, 2007, Chris Messina, a former Google employee, tweeted, "How do you feel about using # (pound) for groups." And that was that. Twitter made it happen, and it became a defining characteristic of the network — and really an integral part of every social network.

On Twitter alone, there are roughly 125 million hashtags shared every day. #NowPlaying is the most shared hashtag of all time, while #Rio2016 was the top hashtag of last year.

So, out of those 125 million hashtags, how do you discover the ones that benefit your brand? Below, learn how many hashtags you should use and find hashtags that will help others find your company.

1. Set a goal

On Twitter, use one or two hashtags for the best engagement rates. Once you use more than that, your engagement actually drops by 17 percent, found Buddy Media data.

On Instagram, aim for at least four or five hashtags for a 63 percent engagement boost, according to TrackMaven data. Here, you have much more flexibility since you can put hashtags in the comments section instead of the post itself. That way, your copy stays clean, and you can jam up to 30 hashtags in a comment.

2. Follow the trends

Plugging into trending hashtags is a great way to get exposure for your business. People are clicking, scrolling and discovering new accounts all the time. In short, using trending hashtags can help garner new followers or boost engagement for that specific tweet. But those eyeballs likely won't belong to your primary demographic.

To find trending hashtags, go to your Twitter homepage and scroll through the trends on the left-hand side. To whittle it down, click "Change" next to the "Trends for you." Enter a location you're targeting, and discover the top hashtags in that area in addition to the global trends you already pinpointed.

On Instagram, go to the "Explore" tab and scroll through the top hashtags.

Remember, on both platforms, only integrate trending hashtags that benefit your brand. Just because a hashtag is popular doesn't necessarily mean you want to be in that conversation.

3. Get specific

Industry-specific hashtags are where you want to focus. This way, you know you're connecting with people who are more likely to become customers.

To find the best hashtags for your company, start by checking which tags your competitors and industry influencers are using. Chances are you should be using many of those same tags.

From there, set aside some time. You'll want to start high level by searching for your industry or top keywords, like "shoes" or "flowers." Look at the results, add filters and investigate the related searches. You should do this on both Twitter and Instagram since hashtags are generally platform-specific.

Create a list of hashtags to try, and track the analytics to see which work best for you.