.htaccess file - What is it used for, how to set php memory, how to setup dynamic urls, how to setup redirects

What they are/How to use them

Technical Definition

.htaccess files (or "distributed configuration files") provide a way to make configuration changes on a per-directory basis. A file, containing one or more configuration directives, is placed in a particular document directory, and the directives apply to that directory, and all subdirectories thereof.

Simple Definition

It's a file that allows you to make changes to the way php/apache behaves and to it's resources.

Things you can do: (by placeing these lines within the .htaccess file) one per line.

Alter / increase the memory allocation for php:

php_value memory_limit 20M

Redircect one page or directory to another

Redirect /olddirectory/oldfile.html http://yoursite.com/newdirectory/newfile.html

You can also place codes after the word Redirect which will tell search engines and browser how they are to handle the redirect:

Redirect 301 - moved permanently

    * 301 - Moved Permanently
    * 302 - Moved Temporarily
    * 403 - Forbidden
    * 404 - Not Found
    * 410 - Gone

# seo friendly redirect for a single file
Redirect 301 /old-dir/old-file.html http://domain.com/new-dir/new-file.html

# seo friendly redirect for multiple files
# redirects all files in dir directory with first letters xyz
RedirectMatch 301 /dir/xyz(.*) http://domain.com/$1

# seo friendly redirect entire site to a different domain
Redirect 301 / http://different-domain.com

Setting MIME types in .htaccess

Add the following line format:

addtype mimeType fileExtension

Examples:

addtype text/vnd.wap.wml wml
addtype application/vnd.wap.wmlc wmlc
addtype image/vnd.wap.wbmp wbmp
addtype text/vnd.wap.wmlscript wmls
addtype application/vnd.wap.wmlscriptc wmlsc
addtype application/vnd.wap.xhtml+xml xhtml