From the lead page ofWebsite
Design & Maintenance: A website might function well with your computer equipment, however, websites must be designed for a wide variety of displays and web browsers to be effective. Every effort should be made
to provide visitors with a pleasant experience, which will lead to desired results.
One of the first considerations for website design is 'content width' - size of the web browser window.
Though most visitors are accustom to a reasonable amount of vertical scrolling (all computer keyboards provide 'page up' & 'page down' keys), horizontal scrolling is annoying and distracting (there are no 'page right' & 'page left' keys).
Example - why horizontal scrolling is bad !
Content width and height are most often is described in pixels or percentage.
The number of pixels used to display content depends on the visitor's computer equipment.
You can resize your web browser window to see how content is displayed at various widths.
Also, you can zoom in & out (zoom feature usually found in the view menu of your web browser)
For you reference, this red line is 400 pixels wide and 20 pixels tall:
See about for examples of websites that do not require horizontal scrolling when viewed with most displays and web browsers.
