How information becomes classified by the US government

— -- A criminal complaint filed Monday against a government contractor in Georgia alleged to have shared classified materials about Russian efforts to interfere in the 2016 presidential election continued to shine a spotlight on the role of government leaks under the leadership of President Donald Trump.

Reality Leigh Winner of Georgia was arrested Saturday after investigators discovered evidence that she printed a confidential intelligence report and mailed it to online news outlet The Intercept. The accusation against Winner comes as Trump has spent much of his first few months as president decrying leaks of classified information -- be they about surveillance, foreign intelligence or White House conversations.

The president himself is reported to have shared confidential information with members of the Russian government during a meeting in May. Trump's authority to declassify information as he sees fit prevents his own action from being considered illegal.

But what does it mean when information is classified?

The current classification procedure originates with an executive order signed by President Barack Obama in 2009, the most recent in a succession of orders that govern how such material is handled.

As with the seven preceding executive orders on the subject, ranging back to President Harry Truman, Obama's action defines what constitutes confidential information, who has the authority to denote such information as classified and the levels and categories of classification.

Obama’s order allows a finite number of officials to classify information. The list includes the president and vice president, in addition to giving the president the right to delegate classifying authority to agency heads and officials. These appointed authorities also have the privilege to delegate classification power to their high ranking subordinates.

Under Obama’s action, classified information can be categorized as either "Top Secret" or "Confidential." Only the president, vice president and their direct classification appointees have the authority to categorize information as "Top Secret," while all other authorities have the right to classify under the "Confidential" status.

Once appointed as an authority, Obama mandated that all officials undergo standardized classification training.

In addition, he outlined authorities permitted to declassify information, allowing those who classified the information to declassify such information. If the authority who originally classified no longer holds their previous office, their successor has the right to declassify such information. These successor’s superiors also have the right to declassify information given that they are trained in Confidentiality.