A joint venture is a structure where two or more businesses bid and perform as one, sometimes through a separate legal entity, sometimes through an agreement alone, most commonly used to pair a small or certified business with a mentor or partner for work it could not easily win solo. Done right, an SBA-approved joint venture, often tied to a mentor-protégé relationship, lets the small partner bid on set-aside work without the arrangement being treated as making it too large or too affiliated to qualify. Done wrong, that same structure is exactly what triggers an affiliation finding, so the paperwork and the specific SBA rules matter as much as the business relationship itself.

In a sentence

"The joint venture between Company A and Company B is approved under SBA regulations to bid on this 8(a) set-aside." That approval is doing real legal work, it is what lets two separate companies bid as one without the smaller partner losing its size or certification status.