It's an important step. Beforehand, voters needed to send off a form in the post. That form can easily get lost, people procrastinate, and the task can be put off.
This year Twitter and Facebook are among the companies that have been encouraging the general public to get themselves registered. And it has paid off.
Some 2.75 million people have registered to vote online this year. That's more than 10% of the 27.1 million people that voted at the last General Election in 2010. Those stats are from Bruce Daisley, Twitter's vice president of Europe, who was presenting at The Financial Times' FT Digital Media conference in London on Tuesday.
Of course, not all of those 2.75 million online registrations will be additive to the total. Many people (this author included) simply registered online because it was easier.
But there's little doubt the new process has worked to prompt people to ote who otherwise may have forgotten.
Daisley highlighted that Twitter embedded messages within its platform to encourage people in the UK to register to vote as time ticked down towards the deadline.
Here's the message UK Twitter users saw with a week to go.

Bruce Daisley/Twitter
And this chart shows how registrations really spiked on the last day:

Bruce Daisley/Twitter
And here's the net result of everyone's efforts:

Bruce Daisley/Twitter

Bruce Daisley/Twitter
Daisley said: "Opinion polls don't take this into account, that 10% of the electorate has been added through online registration."
After TV, the internet has overtaken newspapers to become the second biggest single media by which people receive news, Daisley said.
And the impact of Twitter, especially among young people, is becoming bigger: "34% of 18 to 34-year-olds say they have had their opinion change on who to vote for by Twitter," Daisley said.
Political parties have also been paying for Twitter ads. Daisley didn't mention which parties, or how much they spent (beyond that they were spending less on Twitter
However, Daisley probably meant their organic use of the platform, here, rather than through paid-for Twitter campaigns.