Consider the World Wide Web Consortium Web Content Accessibility Guidelines (WCAG 1), Checkpoint 10.5:
“Until user agents (including assistive technologies) render adjacent links distinctly, include non-link, printable characters (surrounded by spaces) between adjacent links. ”
Generally when trying to ensure that my web pages meet this particular requirement I’m thinking about navigation bars; I’m either marking them up as lists, or putting printable characters between adjacent links (if necessary I make them invisible via CSS).
Unfortunately that isn’t always enough to ensure a clean bill of health with regard to this particular checkpoint. It is easy – particularly on a page that gets updated often – to violate this rule in the bodytext of the page, e.g., when a sentence that ends with a link, is followed by one that begins with a link.
The solution is to get into the habit of adding the full stop after the anchor tag; simple but effective. As web accessibility tips go – it’s not the most significant one I’ve ever published. However, having adjacent links without a printable character between them, means your well-crafted page won’t pass WCAG Priority 1; and someone is bound to get in touch to alert you to that fact.