Most of the professional schools in the United States use an application service to facilitate the application process. An application service receives all the required information a student must submit as part of the application, verifies the information, and then distributes the student's application packet to each school the student wishes to apply to.
All of the application services are found online. You initially register with the application service and at this time you are assigned a unique ID number. Once you have registered, you may begin completing the online application. Once you have completed the application, uploaded all the required documents and paid the fee, you can submit your application. The application service will then be responsible for keeping all of your application documents together as a unit, verifying information you have provided, and then distributing your application packet to the schools you have indicated you wish to apply to. Most of the application services have some sort of "dashboard" area where you can monitor the status of all aspects of your application.
Note that many professional schools also require applicants to fill out a secondary application. Secondary applications are produced and provided by each individual school, not an application service, so it will be your responsibility to find out whether schools you are applying to require secondary applications, and if so, what the timeline and requirements are for submitting them.
Naturopathic medical schools and chiropractic medical schools do not currently have a centralized application service. Apply individually to each school you are interested in attending. Note that even though a centralized application service may exist, not all schools participate in the application service process. Check and make sure that schools you want to apply to participate. If they do not you will have to apply to these schools independently.
Texas residents who are applying to any of the eight public medical schools (seven allopathic, one osteopathic), any of the three Texas dental schools, or the single Texas veterinary school MUST apply through TMDSAS. The Baylor College of Medicine is the only Texas medical school that does not participate in TMDSAS, but it does participate in AMCAS. Non-Texas residents applying to medical school or vet school must use TMDSAS as well. Non-Texas residents applying to dental school may submit applications to the Texas dental schools through AADSAS.
This application service is used for students who wish to apply to allopathic medical schools. If you are a Texas resident and want to apply to Baylor or any medical schools outside of Texas, you will use AMCAS. In addition, students interested in joint programs (e.g. MD/PhD, MD/JD, etc.) typically use AMCAS to apply to these programs. This includes several of the Texas MD/PhD programs!
This application is used for students who wish to apply to osteopathic medical schools. Texas has one osteopathic medical school; you will apply to this school through TMDSAS; use AACOMAS for all other osteopathic medical schools.
This application service is used by students who wish to apply to dental schoolsoutside the state of Texas or dental schools with joint (e.g. DDS/PhD) programs.
This application service is used by students applying to physician assistant programs. Not all PA programs use CASPA so check whether schools you want to apply to uses CASPA or not. All seven of the Texas PA programs require students to apply using CASPA.
This application service is used by students applying to optometry schools. All 21 of the optometry schools, including the two optometry schools in Texas, require students to apply through OptomCAS.
This application service is used by students applying to podiatric medical schools. All nine colleges of podiatric medicine require students to apply using AACPMAS. Texas does not have a college of podiatric medicine.