The size of a cell phone being particularly small, this is not always obvious to visit certain internet sites.
Often it can be seen that the sites are not intended to be viewed properly with a mobile phone.
When the site contains a broad enough picture or dialog boxes containing buttons, the user can encounter real difficulties to navigate. It happens that the text disappears, images prevent to read all of the text or the text appear in small. Worse still, sites designed by artists can become very ugly looking from a cell phone.
What are the reasons?
First of all, most sites have been created well before the rise of cell phones and many have not adapted their site.
There are some who do not want to write several versions of their site adapted to the large and small screens. They prefer to write programs that change dynamically css file on the basis of resolutions or develop css files responsive that make floating objects and put them in accordance with proportions. This has the advantage of not to multiply the number of page html, but the disadvantage of not always properly fit the small screens. The problem comes especially from images that do not change size and objects which are positioned vertically but not always correctly.