This article is an expanded version of a comment I left for someone on another platform.  It was spurred on by their suggestion that by not voting one has given up all their rights.  I inquired if they wanted to know why they were exactly wrong, and that the opposite is true.  Interest was expressed, and so I threw together the following, with some additional explanation.

This is very complex subject matter.  I've tried to explain it in a way that makes sense while leaving out an incredible amount of detail.  I've provided citations and links where relevant so you know I'm not just pulling this out of my ass.  I've tried to present this in a way that requires the least amount of interpretation but as with any esoteric work it cannot be properly understood without the requisite initiation.

Unto you it is given to know the mystery of the kingdom of God: but unto them that are without, all these things are done in parables. -  Mark 4:11 (KJV)

I will address the many questions this material may well evoke in the comments, and will attempt to clarify any points I did not adequately explain.

This mini-treatise may leave you unsatisfied, but that would be because I'm showing you only the mouth of the cavern.

Let's start with the California Constitution, Article II, Section 2:

A United States citizen 18 years of age and resident in this State may vote.

And then in the California Elections Code:

2101. (a) A person entitled to register to vote shall be a United States citizen, a resident of California, not imprisoned or on parole for the conviction of a felony, and at least 18 years of age at the time of the next election.

Note the citizenship requirement.  You'll find similar language in your state constitution and elections code (or equivalent).  You might be wondering by now, huh?  But, look at the terms used: you must be a "United States citizen", and "resident" in California.  Does it mention anything about a California citizen?  Why not?  Aren't the laws and codes of California decided by Californians in a California election?  Of course California only wants Californian's voting in its elections, but the constitution and codes are not saying that.  They says you just need to be a United States citizen and resident in California.

"As 'domicile' and 'residence' are usually in the same place, they are frequently used as if they had the same meaning, but they are not identical terms, for a person may have two places of residence, as in the city and  country,  but only one domicile.  Residence means living in a particular locality, but domicile means living in that locality with intent  to make it a fixed and permanent home.  Residence simply requires bodily presence as an inhabitant in a given place, while domicile requires bodily presence in that place and also an intention to make it one's domicile." - Black's Law Dictionary (Revised Fourth Edition), from case citation under RESIDENCE, p. 1473.

Is someone domiciled in Alabama eligible to vote in California if they can give an address in California where they are resident (assuming they meet all the other requirements, e.g. not being registered to vote elsewhere, of the age of majority, not a felon, etc.)?  Sure, because they are also a United States citizen.