Courses are any resource that intends to teach you the language in a structured way. Different types of courses have different strengths. Some types of courses are only limited to ability in specific domains.
Teach yourself
This type of course relies on the learner focusing and teaching themselves. Little to nothing is done to enforce structure or lesson completion. Learners who use this type of resource should be self-motivated.
websites
Openculture: links to lessons for 45+ lessons
Assimil (paid)
BBC Languages (free)
Live Lingua Project (free resources)
FSI, DLI, and Peace Corps language courses
OpenLearn (free)
edX (free)
MIT OpenCourseWare (free)
50Languages (free)
books
Online courses
Duolingo (free)
LingVist (paid)
Busuu (free with paid premium)
Glossika (paid)
Babbel (paid)
Mango Languages (paid)
StoryLearning (paid with a free 7 day trial)
Rocket Languages (paid)
Listen-and-repeat courses
This subtype of course focus specifically on audio and speech. They are classed separately.
Language Transfer (free)
Coffee Break Languages (free)
Pimsleur (paid)
Tutor websites
Tutors should not be considered a course, but they are able to structure your learning and explain the language, meaning they meet the criterion for a course here. Find them in the section Practice resources.