2 types of these language are used: A) Transitional phrases and B) Connecting clauses.
A) Transitional Phases: The transitional phrases “comprising”, “consisting essentially of”, “consisting of” and "having" define the scope of a claim. Transitional Phases defines what is included and what is not included.
"comprising”, also refer as “including,” “containing,” or “characterized by,” is inclusive or open-ended and does not exclude additional step/method/ingredients.
“consisting of” excludes any element, step, or ingredient not specified in the claim. This is why most of the Pharma company patents include consisting of.
“consisting essentially of” it basically limits the scope of a claim to the specified materials or steps but do not materially affect the basic and novel characteristic of the claimed invention.
“having” it is interpreted in light of the specification to determine whether open or closed claim language is intended.
B) Connecting clauses
I have mentioned about few key features. Others can even include in this one.
For further information, there are few links https://www.uspto.gov/web/offices/pac/mpep/s2111.html, http://www.epo.org/law-practice/legal-texts/html/caselaw/2016/e/clr_ii_e_1_13.htm