When we heard the word keywords a number  of words comes in our mind, this will be used to search on search engines, When we search anything on search engines we are searching within the particular search engine database.

Here are some different types of keyword which we used for search on search engine.

1.Primary : This type defines the nature of business.

2.Secondary : This Type of  defines the product and services website is offering.

3.Sub Primary : This type of  which enhance the quality of a primers keywords, simply add any adjective in front of any primary  it becomes sub primary keywords.   e.g – buy branded shoes

4.Sub Secondary: This type  enhance the quality of secondary keyword add any adjacent to keyword make it sub secondary. e.g, sea facing villa

5.Money : This type  contains any financial terms. e.g, buy shoe online

6.Seasonal : This keywords are used only during some particular time of year, When any festival comes,
e.g, buy rakhi gifts.

7. Long Tail : This type are contain more than 3 words. e.g, how to learn digital marketing.

8.Short Tail : This Type  contain 3 words or less than 3 words.

Some other type of keywords are:

High Search
Low Search
High Competition
Low Competition
(competition refers as number of results in SERP)
Exact Match
Phrase match
Broad Match

With this list one can easily research keywords for their business which can be useful for SEO, and creating ppc campaign.

Mention some if I missed to list here