The FBI has released a summary report of its investigation into Hillary Clinton's private email server, as well as notes from an interview between the bureau and Clinton.

Clinton said she "took all classified information seriously."

The Justice Department has already declined to prosecute Clinton for mishandling classified information, but the documents provide more details on the FBI's probe.

In one note from the documents, the FBI writes that Clinton said she did not know what the marking (C) — used to denote classified information deemed "confidential" — meant. When presented with an email chain using the (C) mark, Clinton "speculated it was referencing paragraphs marked in alphabetical order," according to the report.

The FBI said it questioned Clinton about other levels of classification, such as "top secret" and "secret." Clinton responded that she "took all classified information seriously."

The FBI's report also highlighted some security concerns surrounding the private server. The bureau noted that after a report on Clinton's email server was published by the New York Times last year, there was "an increased number of login attempts to the PRN Server," although none were successful. Similar attempts to break into an associated iCloud account also failed.

FBI said there was "an increased number of login attempts" after New York Times report

As flagged by The Washington Post, the report also says a notice sent to all of the State Department on Clinton's behalf “recommended employees avoid conducting State business from personal e-mail accounts due to information security concerns.” Clinton told the FBI she didn't remember that notice.

The bureau's report also provided some information on Clinton's mobile device habits. "Investigation determined Clinton used in succession 11 e-mail capable BlackBerry mobile devices associated with [redacted phone number], eight of which she used during her tenure as Secretary of State," according to the FBI’s report. "Investigation identified Clinton used two e-mail capable mobile devices associated with [redacted number] after her tenure." The bureau also said it identified five iPads associated with Clinton's private email, and obtained three of them.

In July, when the FBI first announced its findings from its probe, it recommended that charges not be filed against Clinton, although Director James Comey at the time called Clinton's actions "extremely careless."