One of the keys to successful long-term investing in the share market is being able to identify companies that have the ability to consistently grow their earnings into the future.

This is important because shares are valued on their future earnings and a fast growing company is typically worth a lot more than a company with declining profits.

Working out a fair price is usually more tricky and investors should always consider their own risk appetite to help determine a suitable margin of safety when it comes to high growth stocks.

With that in mind, here are three shares that I think have exceptionally strong growth prospects ahead of them:

a2 Milk Company Ltd (Australia) (ASX: A2M)

a2 Milk has already produced some pretty impressive growth over the last few years but I am fairly confident the company will be able to maintain a strong level of growth for a number of years to come. The demand for its baby formula products continues to go from strength-to-strength and it appears sales into China have remained strong, despite new import restrictions.

a2 Milk is now worth more than $1.4 billion, and while this would hardly be considered a bargain based on today’s profitability, I think this is a valuation the company could easily grow into.

As such, I think investors should have it at the top of their buying list should a significant pull-back occur.

Freelancer Ltd (ASX: FLN)

Freelancer is already the world’s largest freelancing and crowdsourcing marketplace and its impressive growth trajectory is highlighted in the slides below.

Source: Company Presentation

Source: Company Presentation

Importantly, the company is now on the cusp of becoming profitable and has recently become operating cash-flow positive. These are important steps in helping to justify Freelancer’s pretty lofty valuation and the company will need to continue to make progress to keep investors on-side.

The share price can be very unpredictable and volatile at times, so I would suggest investors remain patient for a suitable buying opportunity.

iSentia Group Ltd (ASX: ISD)

iSentia shares have taken a beating over the past few months as investors have questioned whether the media monitoring and intelligence company’s growth prospects in Australia have diminished.

Despite these doubts, the company recently re-affirmed its full year guidance and this should provide investors with some confidence that the company is still finding ways to take advantage of the boom occurring in the digital and social media spaces.

The company also has a number of opportunities in the Asia-Pacific region to boost growth and I expect iSentia to remain the clear market leader in the region for a number of years to come.

Looking for more growth shares that you can add to your portfolio right now?

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Motley Fool contributor Christopher Georges owns shares of iSentia Group Ltd. The Motley Fool Australia owns shares of A2 Milk. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy. This article contains general investment advice only (under AFSL 400691). Authorised by Bruce Jackson.