IT procurement documents are popularly known as RFx documents. This a term that includes different stages of the procurement process. When you refer to RFx, it references the formal requesting process. RFx documents are categorized as RFP, RFI, or RFQ documents.

Solution architects are often involved in the procurement process to provide their input or lead them. These procurements may be related to outsourcing, contracting, procuring a software such as a database or development tools, or buying SaaS solutions. As these documents could be highly technical and have a long-term broad impact, the solution architect needs to provide input, or respond to any procurement requirement and prepare the invite. Let's understand the difference between different RFx documents, as follows:

• RFI: RFI comes early in the procurement process, where buyers invite information from different vendors to make an informed decision regarding their choice of procurement for a later stage. An RFI document collects information about the capabilities of the various suppliers, where the buyer can compare all suppliers in a similar parameter and proceed to the next proposal steps with shortlisted suppliers. 
• RFP: In this process, shortlisted suppliers from the RFI process have more information about the outcome of the project. An RFP document is more open than an RFI one, where suppliers can provide the best way to acquire solutions for the buyer. The supplier can include multiple choices, with pros and cons of each approach.
• RFQ: In this process, buyers narrow down the requirement compared to the RFP and list down the exact requirement of work, equipment, and supplies. Suppliers need to provide a cost for the listed requirements, and the buyer can choose the best quotation among them to award the contract.

RFP is the most popular choice, as often, to speed up the process, buyer's organization choose to ask for the RFP document only from potential vendors. In such a situation, the RFP document needs to have the structure in place so that that buyer can put a clear comparison between preferred vendors in terms of capabilities, solution approach, and cost to make a quick decision.

Due to technicalities of procurement in IT organizations, solution architects play an essential role in evaluating vendors' capabilities and approaches from the buyer side or responding to RFP documents from the supplier side.