StocksTwits is Twitter for the investing world.

It has an incredible 1.4 million users. They chat about stocks, bonds, currencies, futures, oil, gold, etc. StockTwits is a great way to gauge market sentiment and hear what other investors think about the hot stocks of the day.

Users post short tweets (you can actually link your StockTwits and Twitter accounts) sharing thoughts about a stock or the S&P 500 index. You can also indicate if you're bullish or bearish.

It's entirely free to sign up and use. The company even has a really cool annual conference called StockToberfest for investors to meet up in real life.

StockTwits co-founder and CEO Howard Lindzon says the platform is useful for both beginners trying to learn more about the investing world and experts who want to engage in deep debate.

Lately, StockTwits has partnered with groups like Robinhood, Fidelity and Scottrade to bring even more retail investors into the conversation. You can automatically create a watchlist on StockTwits to make sure you know the latest about the stocks you own.