The Stone Roses will take to the stage later to headline the opening night of T In The Park.
The Manchester band, which has released new material for the first time in 21 years, will play the main stage at Strathallan Castle in Perthshire.
Jamie XX, Disclosure and Courteeners will also play on Friday, before Calvin Harris and the Red Hot Chili Peppers headline the weekend nights.
The campsite opened on Thursday, with thousands of people arriving early to pitch their tents in the sunshine.
It is the second time the festival has been staged at Strathallan and organisers have made a number of changes to the layout to improve security and avoid the major traffic congestion experienced last year when some people demanded refunds after being unable to leave the park.
DF Concerts apologised and set up a new transport plan for this year's event, including separate roads for buses and cars at the site, an improved bus station in a new location, new car parks and a dedicated pick-up and drop-off point.
Festival director Geoff Ellis said: "The moment we open the T in the Park campsite gates and welcome the first campers is always my favourite part of the weekend.
"It's an amazing feeling to see the first festival fans arrive. There was a phenomenal atmosphere today, and a great sense of excitement amongst the campers.
"T in the Park fans are truly the best audience in the world, we hope everybody has a fantastic weekend."
Travis, Tom Odell and Jess Glynne are among the other acts performing at the three-day event.