Englishfor English speakers
introductory
—
adjective
serving to open or begin
began the slide show with some introductory remarks
—
adjective
serving as an introduction or preface
—
adjective
(= basic)
serving as a base or starting point
a basic course in Russian
basic training for raw recruits
a set of basic tools
an introductory art course
advertisement
Noun
—
An advertisement is a public notice which advertises something; pictures and writing from a company which many people can see.
There was an advertisement for fruit on the wall. It had a big picture of an apple.