Can I know what's the type of invitation letter?

Hi Shamin, you can make the invitation letter by yourself. The letter should include:
a) Information on the applicant (full name, gender, date of birth, etc.)
b) Information on the visit ( purpose of visit, intended arrival date, place(s) of intended residence, intended duration of residence, arrival and departure dates, relations between the applicant and the inviting entity or individual, financial source for expenditures)
c) Information on you (name, contact telephone number, address, signature of you, etc.)