Twitter, twitter on the wall: The best hashtags of 2015

'Tweeting' as the layman say is in. From gay rights to freedom of speech, this chirpy sounding word has become the lynchpin of the vocal, often youthful expression that speaks out on issues as diverse as cat videos and astrophysics.

Rediff.com takes a look at the great moments on Twitter in 2015, from single Tweets that captured our imagination to hashtags that sparked global conversations.

#PrayForParis: The world united to pay tribute to the victims of a series of deadly attacks in the French capital in November, while locals offered shelter to stranded fellow Parisians with the #PortOuverte hashtag. Photograph: Benoit Tessier/ Reuters

#BlackLivesMatter: What started as a discussion on Twitter became a civil rights movement, amid protests over the treatment of minorities by law enforcement in Ferguson, Baltimore and across the country. Photograph: Carlo Allegri/ Reuters

#RefugeesWelcome: People around the world voice their support for people from the Middle East seeking refuge in Europe. Photograph: Yannis Behrakis/ Reuters

#LoveWins: Twitter celebrated the historic Supreme Court ruling that legalized gay marriage. Photograph: Gary Cameron/ Reuters

#JeSuisCharlie: People paid tribute to the victims of a shooting at the offices of French magazine Charlie Hebdo. Hooded gunmen stormed the Paris offices of the weekly satirical magazine known for lampooning Islam and other religions. Photograph: Stefan Wermuth/ Reuters

#IStandWithAhmed: Twitter users, including President Barack Obama, showed their support for Ahmed Mohamed, the 14-year-old Texas teenager who was arrested after his homemade electronic clock was mistaken for a bomb. Photograph: Joshua Roberts/ Reuters

#HomeToVote:  Irish ex-pats shared their experiences traveling home to vote in a historic referendum on allowing same-sex marriage. Ireland became the first country in the world to adopt same-sex marriage by popular vote, with 62 percent of the electorate backing the referendum. Photograph: Cathal McNaughton/ Reuters

#PlutoFlyby: Space enthusiasts celebrated the historic flyby of NASA's New Horizons spacecraft, which came within 7,750 miles of Pluto’s surface and captured close-up images of the icy dwarf planet. Photograph: NASA

#CallMeCaitlyn: Caitlyn Jenner, formerly known as Olympian Bruce Jenner, introduced herself to the world on Twitter, amassing a record one million followers in just over four hours. Photograph: Carlo Allegri/ Reuters