This info from Yorker International University.
HONORARY DOCTORATE:The Honorary doctorate degree
The practice dates back to the middle ages, when for various reasons a university might be persuaded, or otherwise see fit, to grant exemption from some or all of the usual statutory requirements for award of a degree.
On the visit of James I to Oxford in 1605, for example, forty-three members of his retinue (fifteen of whom were earls or barons) received the degree of Master of Arts, and the Register of Convocation explicitly states that these were full degrees, carrying the usual privileges (such as voting rights in Convocation and Congregation).
An honorary degree or a degree honoris causa (Latin: ‘for the sake of the honour’) is an academic degree for which a university (or other degree-awarding institution) has waived the usual requirements (such as matriculation, residence, study and the passing of examinations). The degree itself is typically a doctorate or, less commonly, a master’s degree, and may be awarded to someone who has no prior connection with the institution in question.
Usually the degree is conferred as a way of honoring a distinguished visitor’s contributions to a specific field, or to society in general.
Honorary degrees are usually awarded at regular graduation ceremonies, at which the recipients are often invited to make a speech of acceptance before the assembled faculty and graduates – an event which often forms the highlight of the ceremony. Generally universities nominate several persons each year for honorary degrees; these nominees usually go through a committee before receiving approval.
Some learned societies award honorary fellowships in the same way as honorary degrees are awarded by universities, and for similar reasons.
Recipients of an honorary doctorate do not normally adopt the title of “doctor”. In many countries, including the United Kingdom, Australia, New Zealand, and the United States, it is not usual for an honorary doctor to use the formal title of “doctor”, regardless of the background circumstances for the award. Notable exceptions to the commonly-accepted usage include:
The recipient of an honorary degree may add the degree title post nominally, but it should always be made clear that the degree is honorary by adding “honorary” or “honoris causa” or “h.c.” in parenthesis after the degree title. In many countries, one who holds an honorary doctorate may use the title “doctor” pronominally, abbreviated Dr.h.c. or Dr.(h.c.). Sometimes, they use “Hon” before the degree letters, for example, Hon DMus.