It has been announced that Picasa will be retired in the coming months for Google to focus on a single photo service, that being Google Photos. The aim is to combine the desktop and mobile experiences into a single product, but that doesn't mean everything you've done on Picasa will be lost forever. Google will be rolling out these changes on May 1, so you still have plenty of time to use Picasa before it's eventually retired.

Should you have photos or videos saved in a Picasa web album and do not wish to move to Google Photos, Google will soon offer a way for you to access all of this content, even after Picasa is retired. (You just won't be able to upload new stuff.) From March 15, Google will cease supporting the desktop application, meaning there will be no further updates, but it'll still be usable.

As for developers and third-party clients, some functions of the Picasa API will be retired. It's worth reminding that nothing will change today, and if you wish to switch to Google Photos, you'll be able to upload new content and organize your stored media just as you would through Picasa. If you do not wish to use Google Photos, you'll have to hold out until Google unveils what new tool will be available to access your content once Picasa is shut down.

Source: Google Blog