Digital signature, similar to the traditional handwritten signature, that person has signed the document. However, different from traditional written signatures, digital signatures of each are stored on the signature of the personal information files. Signed PDF documents help to prevent unnecessary changes. For example, the author may not want the company with the rise of the PDF document after the changes in the signature.
     The first in a document known as the author of the signature signatures. When you add a signature to a document, you can choose whether or not to verify the documents. Verification documents so that you can prove the authenticity of its contents and specify the destruction of documents will not be permitted to verify the status of the change types. In the "signature" label in the detection of document changes. Follow-up to the signature of the document known as an ordinary signature.

     To sign a document, you must select the number of ID card, which contains the certificate you can share with other users of the signature information. You can create self-signed digital ID card, or from a third party provider of access to digital identity. The use of certificates, other users can verify your signature, you should also verify the signatures of other people.

The chart is in PDF form an effective digital signature: