Facebook and Instagram became inaccessible, Tuesday morning, for millions of users around the world and with no explanation forthcoming from the social media company, the internet went into a tizzy.

Facebook users reported various issues including slow loading time (and sometimes the page not loading at all); not being able to send messages via Messenger app; and receiving error messages suggesting that the site is undergoing a maintenance.

The site www.downdetector.com confirmed people's worst fears — that the social network platform was indeed inaccessible. Photo-sharing site Instagram was also inaccessible. Facebook bought Instagram in 2012 for $1 billion in cash and stock. As Facebook and Instagram are both down, it seems that the problem lies with servers used by them.

Fortunately, Twitter was not down and netizens took to Twitter to report the outages, using #FacebookDown and #InstagramDown hashtags.

Tech Times investigated and found that the issues were affecting users mostly in the US, UK, Europe and parts of Australia.

Facebook has confirmed the outage in a brief statement on its page but did not explain why it was inaccessible.

"We are currently experiencing issues that may cause some API requests to take longer or fail unexpectedly," the statement read. "We are investigating the issue and working on a resolution."

Facebook and Instagram have users totaling over 3 billion.

On Monday, Facebook Messenger experienced outage with millions of users complaining that they were having trouble receiving messages or not being able to log in at all. On November 12, Facebook and Instagram experienced a total blackout, which Facebook later attributed as being the result of a 'routine test'.

2018 hasn't been good for Facebook. The social media platform made news for the wrong reasons earlier this year when news leaked that data of 87 million users was improperly accessed by political consultancy, Cambridge Analytica. The news prompted global outrage as well as government inquiries into Facebook's privacy policies.

In late September, Facebook also disclosed that a data breach - its worst ever - affected 50 million users, including accounts of Facebook founder Mark Zuckerberg and COO Sheryl Sandberg. The company, however, assured users that their passwords and credit card information were safe and could not be accessed by the hackers.

Facebook stock also took hammering this year, and on Monday, shares fell over 5 percent due to growing concerns over Zuckerberg's more aggressive management style in recent months that have driven away many executives, as well as slowdown in activity of the social network's young userbase, and ability to generate revenue.