The Associated Press reports:

Arlington National Cemetery on Monday made available to the public a massive electronic database detailing the gravesites of the roughly 400,000 people buried there.
Cemetery officials built the database over the last two years to verify the accuracy of their records brought into question by reports of misidentified graves. Prior to 2010, the cemetery used paper records and maps to track who is buried where.
On Monday at the Association of the United States Army convention in Washington, the cemetery debuted an interactive map available through its website and through a free smartphone app. It uses geospatial technology to hone in on specific graves and can also be searched by name.
The database has been the subject of a painstaking review and even now is not 100 percent complete. Katharine Kelley, the cemetery’s director of accountability, said that about 99.4 percent of the nearly 260,000 gravesites, niches and markers have been verified.
The remaining few deal largely with some of the cemetery’s oldest graves and records, which date to the Civil War. In many cases, it may be an effort to verify the spelling of the first name of a spouse buried at the cemetery among disparate handwritten records.

You can search here by name, birth date, death date, and/or location on the website. An iPhone or Android app is available for download here.

Search results include the name of the person who was buried and the dates of their birth and death. Photos of the front and back of the headstone can also be viewed. Monuments and memorials that commemorate the service of specific military units are also included in the database.