There are many e-learning standards in the market, but some of the most widely used and recognized ones are SCORM, xAPI, AICC, and cmi5. Each of these has its own advantages and disadvantages, as well as features. For instance, SCORM (Sharable Content Object Reference Model) is the most common e-learning standard and allows you to create, package, and launch interoperable and trackable courses across different LMSs. However, it does not support offline learning, mobile learning, or complex interactions. xAPI (Experience API) is a newer standard that captures and stores more varied data about learners' experiences and activities across different platforms. But it requires more technical expertise to implement and manage. AICC (Aviation Industry Computer-Based Training Committee) is an older standard that defines how e-learning content and LMSs communicate via HTTP messages. It is compatible with different LMSs and browsers but outdated. Lastly, cmi5 combines the best features of SCORM and xAPI, allowing you to create, package, and launch interoperable, trackable, and adaptable courses across different LMSs and devices. However, it is not yet widely adopted or compatible with some older LMSs.