WPP, the world's biggest advertising company recorded a £1.5bn annual profit in 2014 and kicked off 2015 on a strong note.For the full year, WPP grew pre-tax profits by 12% to £1.45bn on reported revenue of £11.53bn, which was up 4.6% year over year.The group also posted a 3.3% rise in comparable net sales and said its margin rose 0.3 percentage points, in line with targets.WPP said it continues to benefit from consolidation trends in the industry, "winning assignments from existing and new clients, including several very large industry-leading advertising, digital, media, pharmaceutical and shopper marketing assignments, which partly benefitted the latter half of 2014, but the full benefit of which will be seen in group revenue in 2015".The group also said it's feeling upbeat over 2015, saying it had a robust start of the year with like-for-like revenues rising 6.7% in January.As such, WPP said like-for-like net sales in January were up 3.9%, ahead of the 3.3% growth it recorded for the full 2014 year amid resilience in all of its markets with North America and Britain being star performers.Strong growth was driven by advertising, media investment management, branding and identity, healthcare and specialist communications.As such, WPP is paying a dividend this year of 38.2p a share, up 11.7% from last year."2015 looks to be another demanding year, although a weaker UK pound against a stronger US dollar would provide a modest currency tailwind and positive impact on profits, unlike the fierce currency headwind in 2014," added WPP.