Probate is only necessary if an asset is just in name of deceased.
The answer given does not imply that an attorney-client relationship has been established and your best course of action is to have legal representation in this matter.
A will must be filed. That does not mean a decedent's estate must be opened up, but nothing happens without someone taking action. There is no way of knowing how this will turn out based upon the few facts you have presented. You really need to discuss this mater with with a probate attorney.
I agree with the other two responses. Probate is the process of giving someone (an executor or personal representative), the legal authority to transfer title to the assets of a deceased person. If title is set up in joint names with someone else, or if beneficiaries are designated, then probate will not be necessary and the terms of the Will would not apply.
If there ARE probate assets, then the court will appoint the person nominated in the Will. The executor/PR gathers and liquidates assets, pays creditor claims, and generally "administers" the estate. The interested parties (beneficiaries named in the Will), are given notice of the appointment, a copy of the Will, and an inventory for the estate. Before distributions are sent out, the executor/PR provides the interested parties with a final account, listing income and expenses incurred during probate. The assets are distributed and the estate is closed. That is a gross simplification, of course. There may be many other things that need to happen. Tax returns need to be filed, for example. But the basic idea is the PR is given authority to transfer title to assets and to carry out the decedent's intentions, as expressed in the Will.
*** LEGAL DISCLAIMER I am licensed to practice law in the State of Michigan and have offices in Wayne and Ingham Counties. My practice is focused in the areas of estate planning and probate administration. I am ethically required to state that the above answer does not create an attorney/client relationship. These responses should be considered general legal education and are intended to provide general information about the question asked. Frequently, the question does not include important facts that, if known, could significantly change the answer. Information provided on this site should not be used as a substitute for competent legal advice from a licensed attorney that practices in your state. The law changes frequently and varies from state to state. If I refer to your state's laws, you should not rely on what I say; I just did a quick Internet search and found something that looked relevant that I hoped you would find helpful. You should verify and confirm any information provided with an attorney licensed in your state.
Whether a probate is necessary does not depend upon whether a deceased person ("Decedent") had a valid Will. Rather, it depends upon whether the Decedent owned any probatable assets.
If the Decedent died without a valid Will, the State of Illinois intestacy statute designates the beneficiaries who are to receive the probatable assets.
If the Decedent died with a valid Will in force, then the provisions of the Decedent's Will specify the beneficiaries who are to receive the probatable assets.
Probatable assets are assets that are titled in the Decedent's name alone, and that are not payable pursuant to a beneficiary designation form that the Decedent signed during his or her lifetime.
For example, a bank account or parcel of real estate that is titled in the names of the Decedent and another person as joint tenants is not a probatable asset; upon the Decedent's death, the asset is automatically owned by the surviving joint tenant, as the form of ownership includes a built-in survivorship feature. However, if the other person died before the Decedent, then at the time of the Decedent's death the asset is a solely owned asset and is subject to probate.
A bank account, life insurance policy, IRA, retirement plan, or annuity that is payable via a beneficiary designation form the Decedent signed during his or her lifetime, is not a probatable asset; rather, upon the Decedent's death, the asset is distributable directly to the beneficiary or beneficiaries who are named in the beneficiary designation form.
In Illinois, if a Decedent owns various probatable assets, and if the aggregate value of ALL of the probatable assets does not exceed $100,000, then it may be possible to utilize a Small Estate Affidavit to avoid the necessity of opening a formal probate estate.