An affidavit is a written statement in which the signer or "affiant" verifies that the document is true. They differ from sworn oaths only in that the relevant parties must sign them instead of swearing them out loud.

A master service agreement (MSA) is a legal contract that establishes fundamental agreements between two parties. MSAs allow vendors and clients to agree on basic terms at the outset of a business relationship before any business commences.

The W-9 form is also known as a Request for Taxpayer Identification Number and Certification form. It is a type of IRS form used by businesses to collect tax information including the person’s name, address, and taxpayer identification number (TIN).

A purchase agreement is a contract generally used in transactions where the buyer is purchasing goods instead of services. This type of contract is most common in complex and expensive transactions, such as purchasing real estate or large, specialized equipment.

A quote is an itemized accounting of products or services to be rendered in a business transaction. Quotes differ from invoices in that invoices in that they are typically provided to the customer before work begins and/or products are officially purchased.

A statement of work (SOW) is a document that describes in detail how a project will be executed. The purpose of an SOW is to ensure all parties are aligned on scope, deliverables, execution, and payment before signing an agreement.