The Infor CRM web client is the popular method for users to access Infor CRM. Although it is called a client, unlike the LAN client there is no local element to install. The web client site is an HTML site published through IIS on an Infor CRM web server, and can be accessed through any current web browser. The site can be published on an internal server as an intranet site, or made publicly available on the internet like any any other web site. (You might want to make sure your security is solid if you choose to publish on the internet.)
When using the the Infor CRM web client, you can give it its own authentication, or link accounts to Active Directory and have it automatically log users in who are already logged in to Windows on a recognized account. (The latter, single-sign-on option is generally used only on a site published internally.)
There is also an Infor CRM mobile client. It is scaled-down compared to the full web client, but does have access to all the same data. Like the regular web client, it is an HTML site that is deployed into IIS. It has a very different look, and is optimized for touch screen and the form factor of phones and laptops, but accesses the same CRM data as the regular web client. It can even be accessed from a desktop computer, if desired, though it will look a bit odd as it was designed for smaller, narrower screens.