As noted above, for UCs and CSUs, see https://www.assist.org .
For private and out-of-state colleges, check on their transfer credit web site to see if they have a listing (e.g. USC has a listing, but many do not). Keep syllabus, books, and returned assignments and exams in case you need to document the content of the course to a college you want transfer credit at.
For UCs and CSUs, you self-report all high school and college courses and grades on the application (and they will recalculate GPA from what you list).
For other colleges, you will report all high schools and colleges attended, and either send all transcripts or self-report like with UCs and CSUs, depending on what the college wants.
If you are pre-med or pre-law, remember that college courses and grades from when you were in high school will be included in applications to medical or law school.