Age old people are usually hit with certain health problems. Problems with poor eyesight is one of the common difficulty. To read the content of digital media they either have to depend on corrective glasses or some other assistive technology. Instead if the content on your website can be made resizable up to certain size, cant that solve the problem?
Some websites provide font resizing features. As per web content accessibility standards such features are not necessarily required, however the standards required to have the text on websites should be resizable up to 200% (double the original size) without the loss of content or functionality. Users should not require to use any assistive technologies to perform this task. The resizing of text should be performed with browser zoom features or any developer supplied functionalities.
How to do it
All the modern browsers take care of font resizing without any additional effort from the developers. To support legacy browsers, developers can use relative units for font sizes and containers.
Responsive websites by default take care of flexible font sizes. All that the developers need to bother is to ensure that the browser zoom up to 200% should not overlap the content on other containers or should be moving away from user viewable regions on the screen.