Standing is like an admission rule at a bar. Before you can even get through the door, you have to fulfill certain basic requirements, like being over 21, appropriately attired, and not already drunk and disorderly. And, in determining whether you meet the requirements, the bouncer looks at evidence: your driver’s license, your general demeanor, and your clothes.
Courts have similar rules. In order to even have the chance to get your voice heard, you have to meet a host of requirements: your attorney has to be admitted to the bar (though there are times you can litigate by yourself), you had to have handed in your briefs or motions on time, and you have to be the right person to raise the legal issues. That’s what we call standing. Normally, standing isn’t such a big deal: if you hired me to fix your roof and I just decided not to, you’re clearly the aggrieved or damaged party, so you can sue me for breach of contract.
Standing requirements ensure that courts only spend time on cases where there are actual controversies or conflicts between the parties just like ID requirements at bars ensure that alcohol gets served only to those 21 and over. So, it should come as no surprise that the Supreme Court is interested in whether Windsor v. United States, the Defense of Marriage Act (DOMA) case, and Hollingsworth v. Perry, the Prop 8 case, have been brought by the right people.