There are different ways that you might be charged with a crime, including a drug crime. One of these is that the grand jury issues an indictment. This document means that the grand jury found evidence sufficient to charge the person. It doesn't have anything to do with the person's guilt or innocence.
The grand jury indictment is something that is covered under the Fifth Amendment in the case of federal felonies. If a person is being charged with a felony, this amendment requires that an indictment is obtained in order to prosecute the charge. It is also required for an infamous crime to be prosecuted.
Indictments aren't always made public right away. It is possible for the indictment to be sealed so that the people who are covered in it don't get wind of their forthcoming arrest. This can help to prevent people from fleeing from the criminal justice system.
State courts don't have the same requirement as the federal courts; however, ma state courts do use the indictment process for serious felonies. In some cases, indictments are used for misdemeanors, too.
The purpose of a grand jury is to determine the strength of the prosecution's case. If the grand jury doesn't feel that the case is strong enough, they will issue a no bill finding, which means that they don't feel the case will result in a conviction. Many prosecutors will only send cases they feel are strong before the grand jury.
If you find out that you are being indicted, you need to get to work on your defense right away. This might give you sort of a head start, but make sure that you aren't doing anything that destroys evidence or could be construed as trying to flee from justice.
Source: FindLaw, "What is an Indictment?," accessed Nov. 09, 2017