Is it a sin to look at naked or almost naked girls on the computer?

probably

yes watching it ,is a mortal sin,

-but only if it is your mother.

It is a sin to commit adultery! That's very clear. To see a nude: hard copy, electronic, and/or real ones, it depends; it's relative, subjective. The sin is

the real act: having an "intimate" act with someone who is not your spouse.

Just in this time present time, many are divorced. I suppose they have "intimate" acts with their new partner. Then, that's adultery or fornication. This

one for sure is a mortal sin! Not gray, indeed, absolutely a sin! Just to see

the beauty of person is alright - "If eyes were made for seeing, then beauty

is it's own excuse for being!" God wants us to see the beauty in a person He

created. What about a person who has a beautiful voice? We like to hear the

voice, right? So, people endowed with "beauty" is just sharing it to us. There

is a boundary, though, in sharing this "beauty." If it leads to being away from God, then it becomes more than God; it becomes an idol to obssess with.