Signature itself is mark of the person that nobody can duplicate approving and confirming some action. Signature must be something that nobody can replicate. Otherwise other people can do very bad deals with you, for example buy your house for 1EUR without you knowing.
Traditional ritual has been to write something on the paper that is so complex that court experts can make difference is this written by you or not.
Electronic signature has some function and can be done without the paper. There are several levels and types of electronic signatures because of different digital society levels in different place and opportunities to produce digital signatures.
In European Union under eIDAS framework electronic signatures fall into 2(3) categories:
- Qualified Electronic Signatures (QES). These are real signatures using complex cryptography that absolutely tell who was signing and prove that the document has not been changed after signing and
- Advanced Electronic Signatures (AdES). This is substitute to the QES in countries and places that have not yet developed proper and widely used electronic signature infrastructure. In reality it usually works so that e-mail is sent to your e-mail address and then PDF is produced where is pasted image similar to signature written on paper.
- Simple electronic signature (SES). This is anything else. For example you send WhatsApp message to your friend that you will come to his birthday. In eIDAS regulation this is also electronic signature and if you do not show up then he can sue you in court.
All of these signatures are good in their respective usages. If document signed is of low value and you do not expect any disputes then AdES is fine for you.
However it there is big stakes on play: you are selling your house/car, signing employment contract, making big sales deal/purchase order, applying for bank loan etc they you should definitely look towards QES.