What is an e-signature? The complete guide for 2026

An electronic signature — e-signature, or esign — is any mark, symbol, or process that a person applies to an electronic document with the intent to sign it. That's the definition from the ESIGN Act, and it's deliberately wide. A typed name at the bottom of an email qualifies. A drawn signature on a touchscreen qualifies. A cryptographic certificate applied to a PDF qualifies. The common thread is intent.

Where e-signatures became law

In the United States, the Electronic Signatures in Global and National Commerce Act (ESIGN Act) came into force on 30 June 2000, establishing that electronic signatures are legally equivalent to handwritten ones for most commercial and consumer transactions. The Uniform Electronic Transactions Act (UETA), adopted by 49 states, provides the state-level foundation. In the EU, the eIDAS Regulation has governed electronic signatures since 2016, with eIDAS 2.0 updating the framework in 2024. In the UK, the Electronic Communications Act 2000 and the Electronic Signatures Regulations 2002 established legal recognition.

The three types of e-signature

Simple Electronic Signature (SES): the broadest category. Includes typed names, drawn signatures, clicked agreement buttons, and most mainstream e-signature platform signatures. Legally valid for the vast majority of commercial documents. No specific technical requirement beyond intent.

Advanced Electronic Signature (AES): uniquely linked to the signer, capable of identifying them, created using data only the signer controls, and linked to the signed data so any subsequent changes are detectable. In practice, this means a PKI-based signature with a certificate from a certificate authority. Required in some regulated contexts in the EU under eIDAS.

Qualified Electronic Signature (QES): the highest tier under eIDAS. Requires a qualified certificate issued by a supervised certificate authority and is created using a qualified signature creation device. QES is legally equivalent to a handwritten signature across all EU member states. Required for very specific regulated transactions — high-value financial contracts, public sector documents in some jurisdictions.

What makes an e-signature legally binding

For a simple electronic signature — which covers most commercial use cases — three things establish legal validity. Intent: the signer meant to sign, demonstrated by completing the signing process. Attribution: the signature is connected to a specific person, through their email address, IP address, and device. Integrity: the document hasn't changed since it was signed, proved by a document hash recorded at signing time.

What e-signatures are NOT valid for

The ESIGN Act specifically excludes certain document types. Wills and testamentary documents, adoption and divorce proceedings, court orders, foreclosure notices, certain insurance documents, and consumer utility cancellations cannot use electronic signatures under ESIGN. State law (UETA) may vary. For everything else — business contracts, NDAs, service agreements, employment contracts, lease agreements, purchase orders — electronic signatures are fully valid.

How e-signature platforms produce a legally valid signature

A proper e-signature platform does two things: it displays the signature visually in the document, and it records the signing event. The record includes the signer's email address, the timestamp (to the second), their IP address and location, the device and browser used, and a SHA-256 hash of the document at the time of signing. This record is compiled into a Certificate of Completion and attached to the signed PDF — it's the evidence that makes the signature enforceable.

Frequently asked questions

• Is an e-signature the same as a digital signature? No — a digital signature specifically uses PKI cryptography. An e-signature is the broader term that includes typed names, drawn signatures, and digital certificates.
• Do both parties need to use the same e-signature platform? No — one party creates and signs on their platform of choice; the other party receives a link and signs without needing an account on the same platform.
• How long is an electronically signed document valid? As long as the physical equivalent would be — there's no expiry on a signed contract unless the contract itself specifies one.