A godparent of a Catholic child is called a sponsor. Only 1 is actually required although it's normal practice to choose 2. If there are 2 there should be one of each gender. They should normally be aged 16 or over. (There didn't used to be a rule about age; my godfather was 13.) At least one must be a practising Catholic. The other may be a Christian from another denomination but that person is called a Witness not a godparent or sponsor. Non-Christians cannot be godparents.
Some dictionary definitions of the word sponsor: Godfather or godmother; person who undertakes to answer for another's conduct etc.; introducer of person or things. (Latin spondeo, spons- pledge). Sponsor (s)/godparent(s) at a baptism in the Catholic Church fulfil(s) several roles. S/he/ represents the Laity of the Church (Greek laos - people), introducing the candidate for baptism and welcoming him or her into the church community. If the candidate for baptism is an infant the sponsor(s) make the responses on behalf of the child. Sponsor(s)' long-term obligations/ pledges are to support the parents in bringing up the child in the Catholic faith, and if the parents are unable/ unwilling to do that, it becomes the godparent's responsibility. Godparents have a duty of care for their godchild's soul. They are not required to be foster-parents.
In view of the long-term nature of the role, ideally godparents should be close relatives or close friends of the parents.
My godparents were the 2 relatives who could be bothered to turn up at the church that Sunday afternoon. That's why, by default, I had a 13 year-old godfather. I was the youngest of the family and almost the youngest of the "tribe". (I had 6 aunts & uncles in the parish + 6 in another town + more in Ireland; all except 1 must have been occupied that day.) If those 2 hadn't gone to the church my godparents might have been the parents of the other baby baptised with me. (In that case future family historians might jump to the conclusion that our families were close friends.)
My godmother/auntie used to send me a birthday card and a small gift. She probably attended my Confirmation as she lived in the parish.
My brother (another one), aged 17 was godfather to a cousin in another town. She was her parents' 1st child with 9 aunts & uncles.
We should perhaps translate the expression used by Sinann "he stood for me". Being asked to stand for a child means being invited to be the baby's godparent. One is standing up and answering and making promises in place of the child.
My mother was eldest child. Her godparents were best man and bridesmaid (paternal aunt). A year later her sister's godparents were younger brother of her godfather and another, youngest, paternal aunt. (Her dad was the sandwich-filling in between thick slices of sisters.) I had no idea who those godfathers were. My grandma was an only child. When I got round to looking at Grandma's dad's family I found that those godfathers were sons of his cousin, so 2nd cousin to Grandma, 2nd cousin once-removed from my mother and aunt. Great-Granddad and his cousins had lived in the same street as children. The cousins were orphaned and brought up by their eldest sister. I figured that they'd been like brothers and sisters to GGF and his siblings. Besides that, GGF's elder sister married her cousin's widowed husband. GGF & GGM and a cousin & her husband moved from the town where they'd spent their youth to another town. My mother and aunt were born in GGPs' house. Oddly, GGF's religion was recorded as C. of E. on his attestation papers when he joined up for the Boer War.
