Most non-web professionals do not know how to name computer file names correctly. This is probably the biggest bane of “do it yourself” websites because sloppily named files are the number one cause of images not displaying or pages not coming up properly.
When you create a web page or image, you need to save that page as a file within your file system. And for that you need a properly constructed name. While you can name your file nearly anything you choose, there are some rules that do apply to ensure that the page or image displays correctly in the most situations.
Do not use any spaces in your file names
Most operating systems can handle documents with spaces in the file name without a problem, but that is definitely not a good idea for Web page documents. The problem is that when a web address is displayed it is usually shown with an underline. Vistors to your web page may interpret a space as being the underscore character instead, and will not be able to get to your page.
Do not use special characters
For safest results you should only use the letters a-z, A-Z, the numbers 0-9, hyphens (-), underscores (_) and periods (.). Any other character could cause problems, resulting in the file not loading or the page loading incorrectly.
Other tips for naming files
Keep the file names as short as possible for your own convenience and your web visitors too.
Use all lower case to keep things easy. It’s ok to use upper case to help distinguish files such as autosNissan.jpg, etc.
Develop a convention for naming your image files and get organized. This will help you to easily identify your images and web pages. For instance apple001.jpg, apple001a.jpg, etc. could be an easy way to identify images of different types of apples and their sizes or variations.
The end of the file names are important too
When you save a web page the most common choices are .htm or .html. Eitther choice is fine and will dsiplay properly. Other dynamically generated web pages will use file extensions such as .php, .asp, .jsp but for the web novice these will probably not be a concern.
When naming images, the file name extensions are VERY important. An image ending in .jpg should be used for photographs, .gif for illustrations like cartoon graphics or logos (without shading variations). A newcomer in recent years is the .png file which most browsers can now display properly. Under no circumstances should you use .psd or .tif files in web pages as they willl take forever to load and in most cases will prompt the visitor to save the file rather than allowing them to display it.
One final word on photos, especially related to digital camera images
You MUST reduce them to web sizes before adding the photos to a web page and uploading them. Web standards for images are only 72 dpi, which means the images will look good and load quickly. Digital cameras can take and save photos by default in 360 dpi, 720 and much higher. These will load up quickly on your home computer but will take forever on the web. Download a free graphics utility such as Picasa to properly resize your images before uploading to your web page.