Taylor Swift ''can't believe'' she has known Selena Gomez for seven years.

The 'Bad Blood' hitmaker, who is currently on tour in North America, posted a touching message to her best friend on Twitter in honour of her 23rd birthday today (22.07.15).

The blonde beauty, 25, shared a number of photographs of her with the 'Come & Get It' hitmaker, including one of them hugging, on her profile, with the caption: ''Happy 23rd Birthday, @selenagomez. I can't believe it's been 7 years since we met!! I love you so much, always.''

Selena's former 'Spring Breakers' co-star Ashley Benson, 25, also posted a similar tribute on Instagram, writing: ''Happy birthday my sweet angel. It's been so fun watching you grow up over the years. Love you always @selenagomez.''

The 'Heart Wants What It Wants' hitmaker, who split from Justin Bieber last October after four years of dating, enjoyed a low-key celebration at a restaurant to mark the occasion, but thanked her well-wishers for their messages.

Alongside of photograph on Instagram of herself with a slice of birthday cake, she wrote: ''I am the luckiest, happiest girl today. Thank you guys so much for all the bday wishes!! I love growing up with YOU (sic).''