Using tiled-background-image was a popular rage not so long ago, when the web was young.  Arguably, it makes the web more interesting... but often, it could also make a page harder to navigate.  For example, bad choice of colors  without enough contrast, can turn people away from your site.

As the web matures, people began to stay away from using tiled background.  
Be careful when using tiled-image as background, it also can make the text on your page hard to read or even impossible to read.   It can also make your site look unprofessional.  

Still, there are cases where tiled-bacground can enhance your site.  For example, a more popular use tiled background is as a separate layer below a table.  In this way, the background will not obstruct the text, and the text stays readable.  Generally, I prefer to use a background image that is not too complex, as I found too many colors or patterns won't be too pleasant to the eye. 

Some samples of tile images are shown below.  Each images/tile has been designed to appear as a seamless background.  Click on the images/tile to see the tiling effect.  

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