Three terms used interchangeably that mean three different things. Knowing which is which explains a lot of confusing advice about what is and is not allowed.
"Digital signature" and "electronic signature" get used as synonyms constantly, including by people selling both. They are not the same thing, and the confusion produces a lot of advice that sounds contradictory until you sort the terms out.
Ink on paper. The name comes from the ink being literally wet when applied, and it is the baseline everything else is compared against.
Its reputation for security is largely inherited rather than earned. A wet signature proves nothing on its own: handwriting is imitable, the date is whatever somebody wrote, and once a multi-page contract is scanned there is no way to show that page three was not swapped between signing and sending.
What it does have is familiarity and, in a handful of document types, legal necessity. Some deeds, wills and property transfers still require it in some jurisdictions, and where that applies, no amount of technology helps.
The broad legal category: any electronic data attached to or logically associated with a document, used by the signatory to sign.
That definition is deliberately wide. It covers typing your name at the bottom of an email, ticking "I accept", drawing with your finger on a screen, and the full apparatus of a signing platform with timestamps and audit trails. All of these are electronic signatures. They differ enormously in how much they prove.
This is why eIDAS splits the category into three tiers:
Nearly every commercial contract signed electronically is an SES or an AES. QES exists for a narrow set of documents where the law demands it.
Here is where the confusion comes from. A digital signature is not a legal category at all — it is a cryptographic technique. Specifically, it is the use of public-key cryptography to bind a signer's identity to a document in a mathematically verifiable way.
So a digital signature is one of the technologies used to implement an electronic signature. Saying "we use digital signatures" describes a mechanism; saying "we provide electronic signatures" describes a legal outcome. They are answers to different questions, which is why hearing them used interchangeably is so disorienting.
Plenty of things that are not signatures at all use digital signature technology: software updates, TLS certificates, package managers. The technique is much older and much broader than contract signing.
For an ordinary commercial contract — a services agreement, a retainer, a works contract — an advanced electronic signature with a proper audit trail is the right tool and has been for two decades. It is faster than paper and, as evidence, generally stronger.
A wet signature is required for a short list of document types that differ by country and mostly involve land, inheritance or the courts. If your document is on that list, you will usually know, and if you are not sure, that is a real question for a lawyer.
A qualified electronic signature is worth the extra cost and friction only when a specific rule demands it. If nobody has told you that you need one, you probably do not.
Once the terms are sorted out, the interesting question is not which category you are in. It is what happens if the signature is challenged.
Ask any provider: what exactly does your certificate record? If the answer includes per-signer timestamps, IP addresses and a cryptographic hash of the document as sent, the tier label matters much less than the record. If it does not, the label will not save you.
We went through what a good record looks like in what an e-signature audit trail actually proves, and the broader legal position in are electronic signatures legally binding.
General information, not legal advice. The rules differ by country and by document type.
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