prototism

[bear with me while i think out loud, in an attempt to explain my eventual question.]

back before php was popular, most sites were structred with actual, individual html documents, as exemplified below

Code:

/root
  index.htm
  contact.htm
  links.htm
  ...
  /photos
     page1.htm
     page2.htm
     ...

to navigate the website, you would click a link on a page that would link you to an another .htm document (another "page") stored elsewhere on the server. the url would change to reference this new page (ie. example.com/index.htm → example.com/photos/page1.htm)

then php (and sql) came along, and instead of moving from page to page, you simply stayed on the same "page" (usually index.php), and the data "came to you", so to speak (1)

the urls however, were ugly, and enemies of seo. so eventually people wrote some ways to make the url a little more intuitive (ie: blog.com/2009/18/example-post) (2)

now, i say all that to get to my question: how do i accomplish (1) AND (2), on a "flat" website. [by "flat" i mean, everything (for front end purposes) is in root, aka there are no sub folders with linked content pages in them.]

my instincts tell me its relatively simple, but i do not know what exactly to search for on google (or these forums for that matter) to get started. hence, my reason for being here.

i know how to use php include, but that isnt exactly what i am looking for (or it may be, and i just havent explored it enough)

HELP

excuse my improper use of capitalization and punctuation