Is it important to sterilise jars when making marmalade/jam?

Do you have to sterilise them or are they okay with a really good clean and soak in very hot water? Venturing into the marmalade/jam making area as i'm putting together hampers for family at Christmas but the marmalade making stuff (for those in the UK, it's the Ma Made stuff you get in supermarkets) I got just says to wash the jars thoroughly and use them warmed up. But recipes online say to sterilise. Mixed messages make for a confused Becca!!!