Most Wills must be written-word documents. If the Will is composed using a typewriter or a word processor, properly signed, and witnessed, then it will be legally binding in all fifty states. Each page of the Will should be numbered consecutively in a format that expresses the total number of pages (i.e., 3/7, 4/7). The testator and witnesses can also initial each page included in the Will. Another device used to avoid having pages removed from a Will is to have the last sentence on each page continue on to the next page. While the vast majority of Wills are composed as written documents, there are a few other kinds that are valid.
A few states recognize Holographic Wills. These Wills are written in the testator's own handwriting and signed by the testator but do not meet the requirement of having two witnesses. Of the states that recognize holographic Wills, some require that the entire document be in the testator's handwriting, while others only require substantial portions or material provisions to be handwritten. So, some states will allow pre-printed Will forms that are filled in and signed by the testator, while others will not (note: if the pre-printed form meets the usual execution and witness requirements, then it will be accepted by all states - you need only worry about the form if the Will does not meet the witness requirements and is submitted as a Holographic Will.) Given the variety of approaches to Holographic Wills, they should only be depended upon in emergency situations or where the testator wants to make some indication of his wishes before he can execute a valid Will.
Video and Digital-Recorded Wills are a recent innovation. You are recorded reading your Will in front of a camera, and the recording may be used in a court of law to confirm that you were mentally competent when the Will was signed and that the signing of the Will was properly witnessed. Be aware, that while a recorded Will is good legal insurance in the event of some court action, it is very rarely accepted as a substitute for a written will - it only serves as additional evidence in court if the Will is contested. The Will maker should make both a written and a recorded Will.