diff --git a/apps/files_archive/lib/tar.php b/apps/files_archive/lib/tar.php
index a5d54004788f7fe0b6f8a64213ca3795f53b4fc4..1eed11a762d63779323ed1f972d3f82f03e0dd49 100644
--- a/apps/files_archive/lib/tar.php
+++ b/apps/files_archive/lib/tar.php
@@ -30,8 +30,8 @@ class OC_Archive_TAR extends OC_Archive{
 	 */
 	static public function getTarType($file){
 		if(strpos($file,'.')){
-			$extention=substr($file,strrpos($file,'.'));
-			switch($extention){
+			$extension=substr($file,strrpos($file,'.'));
+			switch($extension){
 				case 'gz':
 				case 'tgz':
 					return self::GZIP;
diff --git a/apps/files_encryption/lib/proxy.php b/apps/files_encryption/lib/proxy.php
index c1c26d7754f31c9498ce6983bbef6028c47a9b93..c68df06f9fa22fc2735ff47afed4a91102f6d629 100644
--- a/apps/files_encryption/lib/proxy.php
+++ b/apps/files_encryption/lib/proxy.php
@@ -41,8 +41,8 @@ class OC_FileProxy_Encryption extends OC_FileProxy{
 		if(self::isEncrypted($path)){
 			return true;
 		}
-		$extention=substr($path,strrpos($path,'.')+1);
-		if(array_search($extention,self::$blackList)===false){
+		$extension=substr($path,strrpos($path,'.')+1);
+		if(array_search($extension,self::$blackList)===false){
 			return true;
 		}
 	}
diff --git a/apps/files_sharing/get.php b/apps/files_sharing/get.php
index fa3535fd14457a35d5bed9b7ca86bb09f043961e..3e42bf6a6c71c4b3b73a126d5a5f645829dd0249 100644
--- a/apps/files_sharing/get.php
+++ b/apps/files_sharing/get.php
@@ -31,7 +31,7 @@ if ($source !== false) {
 			if ($i['type'] == 'file') {
 				$fileinfo = pathinfo($i['name']);
 				$i['basename'] = $fileinfo['filename'];
-				$i['extention'] = isset($fileinfo['extension']) ? ('.'.$fileinfo['extension']) : '';
+				$i['extension'] = isset($fileinfo['extension']) ? ('.'.$fileinfo['extension']) : '';
 			}
 			$i['directory'] = substr($i['directory'], $rootLength);
 			if ($i['directory'] == "/") {
diff --git a/apps/media/js/loader.js b/apps/media/js/loader.js
index 514965666fa3bbab05897c306806d37de6c04855..393f8ba914ed41ab0916c7a0f45fc1c8b6ebf38e 100644
--- a/apps/media/js/loader.js
+++ b/apps/media/js/loader.js
@@ -1,10 +1,10 @@
 function musicTypeFromFile(file){
-	var extention=file.substr(file.indexOf('.')+1).toLowerCase();
-	if(extention=='ogg'){
+	var extension=file.substr(file.indexOf('.')+1).toLowerCase();
+	if(extension=='ogg'){
 		return 'oga';
 	}
 	//TODO check for more specific cases
-	return extention;
+	return extension;
 }
 
 function playAudio(filename){
diff --git a/apps/media/js/music.js b/apps/media/js/music.js
index f93f0fded6248be495e65ec6a4985ebf2bdf54e9..db12922762653fbbe86829b8159a80f53ed1f946 100644
--- a/apps/media/js/music.js
+++ b/apps/media/js/music.js
@@ -48,10 +48,10 @@ function getUrlVars(){
 }
 
 function musicTypeFromFile(file){
-	var extention=file.split('.').pop().toLowerCase();
-	if(extention=='ogg'){
+	var extension=file.split('.').pop().toLowerCase();
+	if(extension=='ogg'){
 		return 'oga';
 	}
 	//TODO check for more specific cases
-	return extention;
+	return extension;
 }
diff --git a/apps/media/lib_scanner.php b/apps/media/lib_scanner.php
index 341f411bdb81edfb770ccbd044ad96795de1c254..78c6ad491da32c648e213616dd0d8a072146f59b 100644
--- a/apps/media/lib_scanner.php
+++ b/apps/media/lib_scanner.php
@@ -127,7 +127,7 @@ class OC_MEDIA_SCANNER{
 	}
 
 	/**
-	 * quick check if a song is a music file by checking the extention, not as good as a proper mimetype check but way faster
+	 * quick check if a song is a music file by checking the extension, not as good as a proper mimetype check but way faster
 	 * @param string $filename
 	 * @return bool
 	 */
diff --git a/core/js/js.js b/core/js/js.js
index 2e65dfac507e30ec931b36bed9e22535f2a6ce7f..51dcbe5413e998241cfbdbf6cbcd96d7333981a4 100644
--- a/core/js/js.js
+++ b/core/js/js.js
@@ -69,10 +69,10 @@ OC={
 	 * @param file the name of the image file
 	 * @return string
 	 * 
-	 * if no extention is given for the image, it will automatically decide between .png and .svg based on what the browser supports
+	 * if no extension is given for the image, it will automatically decide between .png and .svg based on what the browser supports
 	 */ 
 	imagePath:function(app,file){
-		if(file.indexOf('.')==-1){//if no extention is given, use png or svg depending on browser support
+		if(file.indexOf('.')==-1){//if no extension is given, use png or svg depending on browser support
 			file+=(SVGSupport())?'.svg':'.png';
 		}
 		return OC.filePath(app,'img',file);
diff --git a/files/css/files.css b/files/css/files.css
index 03945f030b2646d0e5cdbe16116e101fe0cd95b7..e103f0a7a6cbf1bbcee7402622997cd49df0cd4a 100644
--- a/files/css/files.css
+++ b/files/css/files.css
@@ -40,9 +40,9 @@ tbody tr:hover, tbody tr:active, tbody tr.selected { background-color:#f8f8f8; h
 tbody tr { background-color:#fff; }
 tbody tr.selected { background-color:#eee; }
 tbody a { color:#000; }
-span.extention, td.date { color:#999; }
-span.extention { opacity:0; -webkit-transition:opacity 500ms; -moz-transition:opacity 500ms; -o-transition:opacity 500ms; transition:opacity 500ms; }
-tr:hover span.extention { opacity:1; }
+span.extension, td.date { color:#999; }
+span.extension { text-transform:lowercase; opacity:0; -webkit-transition:opacity 500ms; -moz-transition:opacity 500ms; -o-transition:opacity 500ms; transition:opacity 500ms; }
+tr:hover span.extension { opacity:1; }
 div.crumb { float:left; display:block; background:no-repeat right 0; padding:.75em 1.5em 0 1em; height:2.9em; }
 div.crumb:first-child { padding-left:1em; }
 div.crumb.last { font-weight:bold; }
diff --git a/files/index.php b/files/index.php
index 82d09608924c821e6111210cfc2692cb2cbd5671..aea91542db60349fc25b796ccf06a3fe1e002c19 100644
--- a/files/index.php
+++ b/files/index.php
@@ -51,10 +51,10 @@ foreach( OC_Files::getdirectorycontent( $dir ) as $i ){
 		$fileinfo=pathinfo($i['name']);
 		$i['basename']=$fileinfo['filename'];
 		if (!empty($fileinfo['extension'])) {
-			$i['extention']='.' . $fileinfo['extension'];
+			$i['extension']='.' . $fileinfo['extension'];
 		}
 		else {
-			$i['extention']='';
+			$i['extension']='';
 		}
 	}
 	if($i['directory']=='/'){
diff --git a/files/js/filelist.js b/files/js/filelist.js
index 35847e06dfea783a56fb591820e5ae8d0ffe1afa..533e03b43cd214e31aca7c28ccacd54bea3b1098 100644
--- a/files/js/filelist.js
+++ b/files/js/filelist.js
@@ -7,15 +7,15 @@ FileList={
 		var html='<tr data-type="file" data-size="'+size+'">';
 		if(name.indexOf('.')!=-1){
 			var basename=name.substr(0,name.lastIndexOf('.'));
-			var extention=name.substr(name.lastIndexOf('.'));
+			var extension=name.substr(name.lastIndexOf('.'));
 		}else{
 			var basename=name;
-			var extention=false;
+			var extension=false;
 		}
 		html+='<td class="filename" style="background-image:url('+img+')"><input type="checkbox" />';
 		html+='<a class="name" href="download.php?file='+$('#dir').val()+'/'+name+'"><span class="nametext">'+basename
-		if(extention){
-			html+='<span class="extention">'+extention+'</span>';
+		if(extension){
+			html+='<span class="extension">'+extension+'</span>';
 		}
 		html+='</span></a></td>';
 		if(size!='Pending'){
@@ -147,7 +147,7 @@ FileList={
 			span.text(basename);
 			td.children('a.name').append(span);
 			if(newname.indexOf('.')>0){
-				span.append($('<span class="extention">'+newname.substr(newname.lastIndexOf('.'))+'</span>'));
+				span.append($('<span class="extension">'+newname.substr(newname.lastIndexOf('.'))+'</span>'));
 			}
 			$.get(OC.filePath('files','ajax','rename.php'), { dir : $('#dir').val(), newname: newname, file: name },function(){
 				tr.data('renaming',false);
diff --git a/files/templates/part.list.php b/files/templates/part.list.php
index b117d81a1a580b7ecbb871bbaebbd23f0313856d..5a5941fc7ae8f13ec6843c10407a331e64e71913 100644
--- a/files/templates/part.list.php
+++ b/files/templates/part.list.php
@@ -18,7 +18,7 @@
 						<?php if($file['type'] == 'dir'):?>
 							<?php echo htmlspecialchars($file['name']);?>
 						<?php else:?>
-							<?php echo htmlspecialchars($file['basename']);?><span class='extention'><?php echo $file['extention'];?></span>
+							<?php echo htmlspecialchars($file['basename']);?><span class='extension'><?php echo $file['extension'];?></span>
 						<?php endif;?>
 					</span>
 					</a>
diff --git a/lib/filestorage/common.php b/lib/filestorage/common.php
index f632474df01d62f9cae1812d96369f83eab65fab..f0bfc064cb581ae9ed07dcbf64babf7f925eaff8 100644
--- a/lib/filestorage/common.php
+++ b/lib/filestorage/common.php
@@ -100,11 +100,11 @@ abstract class OC_Filestorage_Common extends OC_Filestorage {
 		}
 		$head=fread($source,8192);//8kb should suffice to determine a mimetype
 		if($pos=strrpos($path,'.')){
-			$extention=substr($path,$pos);
+			$extension=substr($path,$pos);
 		}else{
-			$extention='';
+			$extension='';
 		}
-		$tmpFile=OC_Helper::tmpFile($extention);
+		$tmpFile=OC_Helper::tmpFile($extension);
 		file_put_contents($tmpFile,$head);
 		$mime=OC_Helper::getMimeType($tmpFile);
 		unlink($tmpFile);
@@ -129,11 +129,11 @@ abstract class OC_Filestorage_Common extends OC_Filestorage {
 			return false;
 		}
 		if($pos=strrpos($path,'.')){
-			$extention=substr($path,$pos);
+			$extension=substr($path,$pos);
 		}else{
-			$extention='';
+			$extension='';
 		}
-		$tmpFile=OC_Helper::tmpFile($extention);
+		$tmpFile=OC_Helper::tmpFile($extension);
 		$target=fopen($tmpFile,'w');
 		$count=OC_Helper::streamCopy($source,$target);
 		return $tmpFile;
diff --git a/lib/helper.php b/lib/helper.php
index 2026286352a8cddf8d1a4dd2a335439be540cb9d..c33db5f10fe3cd8a1f75951c33603b8f93973026 100755
--- a/lib/helper.php
+++ b/lib/helper.php
@@ -310,9 +310,9 @@ class OC_Helper {
 		$mimeType='application/octet-stream';
 		if ($mimeType=='application/octet-stream') {
 			self::$mimetypes = include('mimetypes.fixlist.php');
-			$extention=strtolower(strrchr(basename($path), "."));
-			$extention=substr($extention,1);//remove leading .
-			$mimeType=(isset(self::$mimetypes[$extention]))?self::$mimetypes[$extention]:'application/octet-stream';
+			$extension=strtolower(strrchr(basename($path), "."));
+			$extension=substr($extension,1);//remove leading .
+			$mimeType=(isset(self::$mimetypes[$extension]))?self::$mimetypes[$extension]:'application/octet-stream';
 
 		}
 		if (@is_dir($path)) {
@@ -346,9 +346,9 @@ class OC_Helper {
 			if(!self::$mimetypes || self::$mimetypes != include('mimetypes.list.php')){
 				self::$mimetypes=include('mimetypes.list.php');
 			}
-			$extention=strtolower(strrchr(basename($path), "."));
-			$extention=substr($extention,1);//remove leading .
-			$mimeType=(isset(self::$mimetypes[$extention]))?self::$mimetypes[$extention]:'application/octet-stream';
+			$extension=strtolower(strrchr(basename($path), "."));
+			$extension=substr($extension,1);//remove leading .
+			$mimeType=(isset(self::$mimetypes[$extension]))?self::$mimetypes[$extension]:'application/octet-stream';
 		}
 		return $mimeType;
 	}
diff --git a/lib/mimetypes.list.php b/lib/mimetypes.list.php
index e0570e84ea5c8c8e758ecc0339b2d7e4d029635e..ccf47999b1cfa1dbbe26c68c814b97405259c6b3 100644
--- a/lib/mimetypes.list.php
+++ b/lib/mimetypes.list.php
@@ -21,7 +21,7 @@
 */
 
 /**
- * list of mimetypes by extention
+ * list of mimetypes by extension
  */
 
 return array(
diff --git a/lib/template.php b/lib/template.php
index cb39a10df31d3fa04a2d5cdc254fc5f57564b5b0..eeba2410b6880bec48cb594a3409b5b02f25e5d8 100644
--- a/lib/template.php
+++ b/lib/template.php
@@ -161,7 +161,7 @@ class OC_Template{
 	}
 
 	/**
-	 * @brief Returns the formfactor extention for current formfactor
+	 * @brief Returns the formfactor extension for current formfactor
 	 */
 	protected function getFormFactorExtension()
 	{