Typical categories include awards, general support, endowments, fellowships, matching funds, continuing support, etc. Grants can be given for projects, or for things like research, scholarships, or seed money. Grantors usually have geographic preferences, ranging from a local district or city, to county, state, or national level. The first place to check out is your local library. Your library will have a variety of books and reference materials that can teach you about grants, and also provide you with names of individuals or organizations that fund grant projects.
Every library has different materials on grants.
More and more libraries are making Internet and a variety of databases available to library users. This is a potential gold mine for grant seekers. On a recent trip to my local library, I found The Art of Winning Corporate Grants, by Howard Hillman and The Basic Handbook of Grants Management, by Robert Lefferts very helpful. In the reference section, the Catalog of California State Grants Assistance, by the California State Library and Vera Nichols, is also a good resource. The updated edition of this catalog titled The Catalog of State Funding Sources '93, lists state and federal grants, as well as loan programs and other funding and assistance offered by state agencies to local governments, special districts, colleges and universities, and nonprofit or community based organizations.