Pessoal alguém sabe me dizer o que e esse data-adblockkey?

Preciso saber pra que ele serve!

<!DOCTYPE html><html data-adblockkey="MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBANDrp2lz7AOmADaN8tA50LsWcjLFyQFcb/P2Txc58oYOeILb3vBw7J6f4pamkAQVSQuqYsKx3YzdUHCvbVZvFUsCAwEAAQ==_LDCB4dgIUC6CVCv3ABz2u9LATaaelhYs/uTyta9Rlagkm0VH5HpDq2GJ0O8ljpkpmJd/YzhScJxWRpNlDT+f1Q=="><head>