Parenting newsflash: teenagers aren't on Facebook anymore.

That's right - Facebook, the social media giant with over one billion active users worldwide, is apparently not that cool with the young people these days. (Damn - thought you were all over that one, didn't you?)

Just ask 13-year-old Ruby Karp, who penned an opinion piece for Mashable earlier this month called 'I'm 13 and none of my friends use Facebook'.

The New York teen explains Facebook is losing her generation's interest for various reasons - their parents and grandparents are using it, the site changes too much, and it's simply not 'trending' anymore. "Facebook has been trying too hard. Teens hate it when people try too hard; it pushes them away," Ruby writes.

A 2013 Pew Internet survey also indicates teens are being turned off by the over-sharing and "drama" Facebook attracts.

But before you fist-pump with relief, there's one point left to consider. A major reason Facebook is losing cachet with kids because it's being crowded out by newer, more exciting websites and smartphone apps. Although it's still holding on to the title of most popular social network for teens, Facebook has some serious competition from the likes of Instagram and Snapchat.

Confused? Downright terrified? Here's a rundown of some of the most popular social media sites among teenagers - and what you need to know about them.

1. Instagram

What is it? Instagram is an app allowing users to take photos and videos, enhance them with vintage-looking digital filters, and share them online. It's quick, easy and way more convenient to carry around than the classic point-and-shoot camera.

Worth knowing: Unlike Facebook, Instagram is purely visual, meaning there are no tedious status updates to scroll through - just endless photos of pets, artfully prepared food and, of course, "selfies". The downside is that many teens - particularly girls - seem to use it as an avenue for self-validation based on appearance and measured by 'likes'. Earlier this year, reports of Instagram beauty pageants  revealed some young women were uploading selfies (self-portraits) to be included in photo pageants voted on, "hot-or-not" style, by their peers and complete strangers.

Instagram photos are publicly visible by default, but privacy settings can be modified to ensure photos are only shared with approved "followers". When an account is private, "follow" requests from other users must be approved in order for them to access photos.

2. Tumblr

What is it?: Tumblr is a "microblogging" platform used to share and reblog images, gifs, videos and short pieces of text. According to the website, Tumblr celebrates "creativity" by encouraging users to reflect who they are and what they "love, think, witness, and believe", by customising and curating their profiles and shared content. Its popularity stems from the ability for users to disguise their identity and the fact that parents are less likely to be found there. It's also easy for Tumblr users to find and communicate with like minds, based on their interests.

Worth knowing: The emergence of "thinspo" (i.e. "thinspiration") and pro-anorexia and self-harm content on Tumblr caused the site to develop a policy banning posts glorifying and promoting this behaviour last year. Pinterest and Instagram have since followed suit. However, these measures haven't been successful in stamping out the problem completely - thinspo communities, where users share photos, words and other posts encouraging extreme weight loss and thinness, have simply migrated to other locations online.

3. Twitter

What is it?: Twitter allows users to share text updates of 140 characters or less  (tweets) with their followers, and to read tweets from users they follow. Videos and photos can also be shared. Users can reply to tweets and tweet to other users, and can retweet posts from others to display on their own profiles. A lot of celebrities and public figures use Twitter, meaning your teenager can follow and receive updates from their idols.

Worth knowing: As with almost any social media site, some people use anonymity as a way to bully or threaten other users. In this instance, Twitter users can 'block' other profiles to prevent them accessing or responding to posts. Recently, Twitter has promised to improve its abuse reporting capabilities and response to 'trolls', following widespread criticism it was not doing enough to curb abusive behaviour (including threats of violence) by users.

As with Instagram, profiles can be made private so that followers need to be granted access to updates.

4. Snapchat

What is it?: Even if you don't recognise the name, you're probably familiar with the concept behind Snapchat. Users can send each photos and videos that self-destruct within seconds of being opened - making it the ultimate tool for sharing those fleeting, insignificant moments that don't need to be archived.

Worth knowing: If you believe the reports, teenagers love SnapChat because it lets them send sexts (i.e. sexy photos) without lasting evidence/blackmail material. However, all is not as regret-free as it seems. According to reports, expired snaps are not actually deleted, merely 'hidden' from the operating system, and can be retrieved with software and apps.  Plus, although the photos 'vanish' after a determined time period, recipients can screencap and save the image as it displays - although the sender will be notified if this happens.

Children under 12 years of age are only permitted to access a limited version of the app called SnapKidz. For more info, check out SnapChat's guide for parents.

5. Ask.fm; Formspring

What is it?: These Q&A-style social websites have a common function: users can post questions - anonymously if they please - for others to answer. Latvia-based Ask.fm launched in 2010, less than a year after its US counterpart.

Worth knowing: The anonymity afforded by both sites has led to several high-profile incidences of cyberbullying - some with tragic endings. Last month, 14-year-old English schoolgirl Hannah Smith committed suicide after enduring months of abuse and threats on Ask.Fm - although investigations into the case have reportedly found the majority of these messages were sent from Hannah's own computer. Hannah's death - and the media coverage that followed - has seen Ask.Fm promise to introduce a "bullying/harrassment" button and to investigate reports of abusive behaviour within 24 hours. It will also force users to register an email address to get full access to the site.

6. Vine

What is it?:  Vine is a video-sharing app owned by Twitter. Users can create video clips (i.e. Vines) with a maximum length of six seconds, which can then be shared on Facebook and Twitter (you can see a live-stream of Vines here). Although the app only debuted in January, its popularity has been enormous - there are currently 4 million registered users. A small survey by Buzzfeed found the majority of Vines were posted by teenagers.

Worth knowing: When it launched, Vine had a 12+ age rating, meaning users were required to 'confirm' they were above that age. However, the app was soon forced to raise this rating to 17 and over after pornographic and adult content began appearing on the site and in the 'Editor's Picks' (as a result of "human error").

Which social media sites are your teenagers using?