Doctype

The DOCTYPE tells the validating parser where to find the DTD or schema it should use for that document.
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
The DOCTYPE declaration consists of several parts
- <!DOCTYPE Indicates to the processor that this is a DOCTYPE declaration.
- html Indicates the name of the root element for the document.
- PUBLIC A DOCTYPE can designate a publicly recognized DTD, potentially saving the processor a trip to the server to retrieve it.
- "-//W3C//DTD HTML 4.01 Transitional//EN": The actual public identifier for the Transitional XHTML DTD.
For custom DTDs, developers typically use a SYSTEM identifier, such as:
<!DOCTYPE memories SYSTEM "/home/jmvidal/memories.dtd">