Of course, sometimes there’s just too much information or too complicated text to use icons for it all. In those cases, some of my (somewhat subconscious) criteria for deciding what type of text are:

* Should the user have the information handy in the future or at different locations? For example, information about a store — the store owner probably wants the user to think of the store at home the next day, so they’ll offer a notecard. Likewise for game sim operators where the user should be able to refer to the game rules and conduct rules without having to return to the start point. On the other hand, if it’s information they only need while at a particular location (e.g. how to use a particular object in the scene), a notecard would not be a good choice.

* Is there a LOT of text the user must read? This is assuming that the amount of text cannot be further reduced; if it can, do that as much as possible. But, if it can’t be reduced, use a notecard for it. A texture showing that much text would be have to be very large, both in prim dimensions for the display, and in download size. And since the user won’t read it all anyway, better to save yourself the texture upload fee and just use a notecard. Floating text is not a good choice for large blocks of text, since it will block the view forever, whereas a notecard can be closed after being (not) read.

* Does it need to update quickly or dynamically by a script? If it needs to be fast and dynamic, floating text is the only way to go. XyzzyText is another option for dynamic text like sign boards, but the glyph texture(s) can be slow to rez.

* Should the user be able to see it before the whole scene has rezzed? If so, textures are out of the question. As a somewhat silly example, making a textured sign that says “Do not walk forward off this cliff!” is just asking for trouble. The user may try to walk before the scene has rezzed and — woops, down they go! In such a case, I’d prefer floating text for information about a specific location, or a scripted “blue box” for general information. Notecards would be last on my list for this purpose. (Of course, if it were actually a cliff, I’d just put a fence to stop them accidently falling off…)

* Another option for text is actually web-on-a-prim, displaying a web page in place of a texture (via the About Land > Media tab). With some clever scripting, it’s even possible to display a different web page to each user. However, it’s only possible for users to see one web page at a time, and they must have streaming media enabled or they won’t see it at all.

* Video and audio are expensive to produce (in money or time/effort), so I tend to shy away from them. Audio also tends to be more difficult for people who don’t speak the language; with text, they can at least run it through an automatic translator. For people with big budgets for production and translation, though, well-done video and audio can be highly effective.