File sharing glossary: 30 terms explained in plain English
30 file sharing terms, decoded
This glossary explains the 30 file sharing terms people run into most, from shareable links and expiring links to magic bytes, signed URLs and MCP servers. Each one gets a short, plain-English definition and, where we have one, a link to a deeper guide. Jump to any term from the list below.
Shareable link · Direct download link · Expiring link · Self-destructing link · View-only link · Password-protected link · Email gate · View limit · Link analytics · Unique visitor · QR code (static vs dynamic) · File transfer · File hosting · Cloud storage · Data room · Peer-to-peer transfer · Signed URL · CDN · MIME type · Magic bytes · Base64 overhead · Attachment limit · Content moderation · Hash matching · MCP server · API key · OAuth · llms.txt · Static site · Custom domain
What kinds of links are there?
Shareable link
A web address that opens a file for anyone who has it, without the file traveling as an email attachment. You send a few characters instead of the bytes, and you can usually change or turn off the link later. Read more: How to share files securely by link.
Direct download link
A link that starts the download straight away instead of showing a preview page first. Useful for installers, datasets and scripts that fetch a file; less useful when you want the reader to look before they save. Read more: Make a direct download link.
Expiring link
A link that stops working at a date and time you choose. Anyone who opens it after that sees a dead page, but a copy someone already downloaded stays on their device. Read more: Expiring PDF links.
Self-destructing link
A marketing name for a link that dies on its own, after a set number of opens, at a deadline, or both. It controls access over time; it cannot erase a file someone already saved. Read more: Send a file that self-destructs.
View-only link
A link where the file opens in the browser but the download button is hidden. It stops casual saving. It is a deterrent, not DRM: a screenshot or a determined person can still keep a copy. Read more: Share a PDF people can view but not download.
Password-protected link
A link that asks for a password before the file loads. Send the password through a different channel than the link, so one leaked message does not unlock the file. Read more: Password-protect a file you share.
Email gate
A form in front of a file that asks the visitor for their email address first. Common for lead magnets, and it turns an anonymous view count into a list of named readers. Read more: Deliver a lead magnet PDF and capture emails.
View limit
A cap on how many times a link can be opened before it stops working. Set it with some headroom, because a refresh or a second device counts as another open.
How do you measure who opened a file?
Link analytics
The record of what happened after you shared a link: how many opens, when, from which country and device, how long people stayed and how far they read. Good analytics leave out bots and link-preview fetches. Read more: Track who opened a shared file.
Unique visitor
One person (or, more exactly, one device and network) counted once, however many times they open the link. It is an estimate: two people on the same office network can look like one, and one person on phone and laptop can look like two. Read more: Why your file views look too high.
QR code (static vs dynamic)
A square barcode a phone camera turns into a web address. A static code holds the final address itself and can never change. A dynamic code holds a short link that can be pointed at new content and counts scans, which is how a printed code survives a file update. Read more: Turn a PDF into a QR code.
What is the difference between transfer, hosting and storage?
File transfer
Moving a file from one person to another, usually once. Transfer services are built for big files and short-lived downloads, and the link typically expires after a few days. Read more: File transfer vs sharing vs hosting.
File hosting
Keeping a file online at a stable address so people can open it whenever they like, often in the browser. It suits files you share again and again: a resume, a menu, a price list. Read more: Free file hosting sites compared.
Cloud storage
A private online drive for your own files, synced across your devices. Sharing is a side feature, so links often open the storage app's own viewer or ask the visitor to sign in.
Data room
A controlled set of documents shared with outsiders during a deal, such as investors or buyers in due diligence. The point is per-reader permissions and a record of who read what. Read more: Data room alternatives for startups.
Peer-to-peer transfer
Sending a file straight from one device to another over an encrypted connection, with no copy kept on a server. Both people must be online at the same time, but there is no upload to wait for. Read more: Send files without uploading them.
What happens behind the link?
Signed URL
A temporary address for a stored file with a cryptographic signature and an expiry time built in. It lets a browser fetch one specific file for a few seconds or minutes, so the storage itself never needs to be public.
CDN
A content delivery network: servers around the world that keep copies of popular files close to the people opening them. The result is faster loading and less strain on the original server.
MIME type
The label that says what kind of data a file is, such as application/pdf or image/png. Browsers use it to decide how to open a file, but it is easy to fake, so a careful host does not trust it on its own.
Magic bytes
The first few bytes of a file, which reveal its real format whatever its name says. A PDF starts with %PDF, for example, so checking them catches a program renamed to look like a document.
Base64 overhead
Email turns attachments into text with Base64 encoding, which makes them about a third bigger in transit. That is why a file just under your provider's limit can still bounce. Read more: Email attachment size limits.
Attachment limit
The biggest email an email provider will send or accept, around 25 MB for most mainstream providers. It applies to the encoded message, so the usable file size is smaller. Bigger files should go as a link. Read more: Email attachment size limits.
How do hosts keep files safe?
Content moderation
The checks a host runs to keep illegal or harmful files off its service: automated scanning at upload, human review of anything flagged, and a way for anyone to report a link. Read more: How file hosts scan uploads.
Hash matching
Comparing a short fingerprint of a file against a list of fingerprints of files already known to be bad, such as known malware. It finds exact or near copies without anyone needing to look at the file. Read more: How file hosts scan uploads.
Which terms matter for developers and AI agents?
MCP server
A service that speaks the Model Context Protocol, an open standard that lets AI assistants such as Claude or ChatGPT use outside tools. Connect a file host's MCP server and the assistant can publish a file and hand you the link in the chat. Read more: What is an MCP server?.
API key
A secret string that lets a script act on your account without your password. Treat it like a password: keep it out of public code, and delete it when you no longer need it. Read more: Upload a file by API.
OAuth
The standard behind "Sign in with..." and "Allow this app" screens. An app gets a limited token to act for you, and you never hand it your password; you can revoke the token later.
llms.txt
A plain-text file at the root of a website that tells AI assistants what the site is and which pages matter most. It is a proposed convention, not a formal standard, and it sits alongside robots.txt. Read more: Content signals in robots.txt.
What about websites and domains?
Static site
A website made only of ready-made files (HTML, CSS, JavaScript and images) with no server code or database. You can publish one by uploading a ZIP of the folder. Read more: Host a static website from a ZIP.
Custom domain
Your own web address, such as files.yourcompany.com, used in place of the host's address. You point it at the host with a DNS record and the host adds the security certificate.
How these terms show up in Link in Seconds
Most of the link controls above are settings on every Link in Seconds link, free on every plan: a password, an expiry date, a view limit, an email gate, view-only mode, a QR code and analytics with unique visitors. Up to 5 custom domains are free too. Uploads are checked by their magic bytes, and stored files are served through short-lived signed links. Website hosting is a Pro feature. See link settings for how each one works.
Quick answers
What is the difference between file sharing and file transfer?
File transfer moves a file to someone once, usually big and usually with a link that expires in days. File sharing is the broader idea of giving people access to a file, often through a link that stays live and that you can control or turn off.
What is a shareable link?
A web address that opens a file for anyone who has it. Instead of attaching the file, you send the link, and you can usually add a password, set an expiry date or turn the link off later.
Is a view-only link secure?
It stops casual downloading, but it is a deterrent, not DRM. Anyone who can see the file can screenshot it. For files that must not leak, add a password and an expiry date, and think about whether the file should be shared at all.
What are magic bytes?
The first few bytes of a file, which show what format it really is regardless of its name. File hosts check them so a program renamed to .pdf is caught before it is published.
Do I need an account to open a shared link?
Not on Link in Seconds. Viewers need no account. The person uploading needs a free account (no card), and every link control in this glossary is free on every plan, with files up to 250 MB on Free.
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