CODE EXAMPLE FOR PHP

url rewrite htaccess php

You can essentially do this 2 ways:

The .htaccess route with mod_rewrite
Add a file called .htaccess in your root folder,and add something like this:

RewriteEngine on
RewriteRule ^/?Some-text-goes-here/([0-9]+)$ /picture.php?id=$1
This will tell Apache to enable mod_rewrite for this folder,
and if it gets asked a URL matching the regular expression it rewrites it
internally to what you want, without the end user seeing it.
Easy, but inflexible, so if you need more power:

The PHP route
Put the following in your .htaccess instead: (note the leading slash)

FallbackResource /index.php
This will tell it to run your index.php for all files it cannot normally find in your site. In there you can then for example:

$path = ltrim($_SERVER['REQUEST_URI'], '/');    // Trim leading slash(es)
$elements = explode('/', $path);                // Split path on slashes
if(empty($elements[0])) {                       // No path elements means home
    ShowHomepage();
} else switch(array_shift($elements))             // Pop off first item and switch
{
    case 'Some-text-goes-here':
        ShowPicture($elements); // passes rest of parameters to internal function
        break;
    case 'more':
        ...
    default:
        header('HTTP/1.1 404 Not Found');
        Show404Error();
}

This is how big sites and CMS-systems do it, 
because it allows far more flexibility in parsing URLs, 
config and database dependent URLs etc.
For sporadic usage the hardcoded rewrite rules in .htaccess will do fine though.