Popular blogging platform Tumblr is opening up its users’ blogs to advertising starting Thursday, allowing bloggers to make money from the revenue so generated. However, if you use Tumblr and don’t want to make your personal blog a commercial space, you can opt out of it.

In an official post from Tumblr staff, the Yahoo-owned company said its users will be able to “start making money from their blogs” starting “later this year.” Other than not having a fixed timeframe, the company is still not clear on the monetary details either. “We’re still working out the details of the partner program but as soon as we have details to share, we’ll make announcements right here,” it said.

Users who want to make money from the ads displayed on their Tumblr blogs won’t just get it automatically, though. They will have to register for the partner program, which has not yet been rolled out. So the ads will start on Thursday, unless users choose to opt out from their blog settings (instructions can be found here), but the money will start coming at some point in the future.

Older bloggers who have used Google’s Blogspot service will not find this offer new and may instead wonder why Tumblr came to the party so many years late. It is impossible to say for certain but it may have something to do with all that’s going on at Yahoo, not the least of which is its $4.8 billion sale to Verizon, soon to be the parent of Tumblr.

There are more than 300 million blogs with over 137 billion posts on Tumblr, according to the company and Alexa ranks Tumblr 46th globally in terms of traffic, with over 550 million monthly visitors.