Some people just want to find out about their direct ancestors. They think that will be enough. They ignore all the external people they find: siblings of in laws, neighbors, business associates, anyone who isn't their direct ancestor. They don't know how addictive this "little" genealogy hobby will become.
Don't fall into that trap. When you find a person who married into your line and you see something about his brother write it down. Often when a person married into a family other siblings and/or cousins also married into the same family. Or maybe they didn't but their children did. You may not know why now but someday you'll wish you had made the notes when you had the chance.
Originally I busily entered my ancestors into my database. This is a time consuming and, I admit, sometimes semi boring process. Naturally I avoided "unnecessary" people. I quickly learned that, sooner or later, I would need those unnecessary folks. Now I enter all sorts of people, even people who are totally unrelated to me [as far as I know today] but who were living in the area. I am no longer surprised when I eventually find a connection.
About 13 years ago I "met" Neal Downing. Back in the 1850s and 60s three children of Samuel Downing married three children of Robert Downing. These lines were previously unrelated, from different parts of the country, but ended up a mile apart in Logan County. I am a descendant of one of those marriages. Neal descends from another. His ancestors left Logan County and moved west - long gone but once they were closely related.
Last winter Neal commented he didn't know as much about his wife's family. In an amazing coincidence her ancestors had also lived in Logan County but moved west. They met in California. He sent me the line they knew, no names I recognized as they were from a different part of the county - until I got to her ancestor Charity Bowman. I did a double take.
I am related to both Neal and his wife. Charity was a sister of Hannah Bowman, my 4th great grandmother. Their mother Mary Senteney Bowman is my 5th great grandmother and Jackie's 4th great grandmother. Hannah, Charity and their mother are all buried in Steenbergen.
Take the time to write down those names and whatever else you run across. You just never know.