Client's logo

Hi, Céline,

This is another question for which the answer is "it depends." 

If a course will be available to people outside the company, then it makes sense to include the company logo (and probably a bit of other info) on a splash screen at the beginning. And the logo could be incorporated into the slides, though I'd avoid it. Or, at least, keep it relatively small and unobtrusive. 

If a course is only for employees, the logo could be included on the title slide (along with any necessary notes, such as "for internal use only"). But I see no need for a fancy splash screen nor for including the logo on every slide. After all, people know what company they work for. (As a learner, I resent having to sit through even a 10-second logo animation that just tells the company name.) 

If the course will somehow be published in a printable/distributable format, then it makes sense to include the appropriate copyright info up front. That could be added separately (i.e., it wouldn't have to appear in the course.

IMHO.