Choose how many GUIDs to generate and the letter case, then copy the returned list. Generation is handled by the website.
Each value in the batch is a 128-bit version 4 identifier — 32 hexadecimal digits in five groups — which is why a GUID and a UUID can be used interchangeably.
A GUID is 32 hexadecimal digits split 8-4-4-4-12, for example 4F1C0A9E-3D2B-4E77-9C51-8A6B0D2E7F34. This page returns version 4, the random variant: the first digit of the third group is always 4, and the first digit of the fourth group is always 8, 9, A or B. Those two fixed positions are what a validator inspects to confirm a well-formed version 4 value.
The bits come from the operating system's cryptographic random source rather than from a counter or the clock, so a value cannot be predicted from the ones printed before it.
The size selector offers 1 to 99. Values inside one batch are distinct: if the generator were to produce the same identifier twice, it draws again instead of printing a duplicate.
Uppercase and lowercase are the same identifier written differently — only the letters A to F are affected, never the digits or the grouping. Both forms compare equal in SQL, in .NET's Guid type and in any parser that reads hexadecimal case-insensitively, so choose the case your target system expects. This page opens on uppercase; the UUID page opens on lowercase.
The form posts to the server and the page returns with the list already filled in, so nothing is generated by your browser. Every submission is a fresh batch, and the result box holds only the most recent one.
This page has no text field, so there is no content of yours to submit: the only values that travel with the request are the batch size and the letter case.
GUID and UUID are two names for the same 128-bit identifier, the first popularised by Microsoft. The UUID page here returns the identical layout and differs only in its default letter case, so either page produces values the other one accepts.
Version 4 values are random and therefore unordered: a newly created record does not get a larger identifier than the one created before it. That matters when the value is a clustered primary key or a pagination cursor — the tab bar above the form links to the other identifier generators on this site for the cases where ordering matters.