what does this mean ? image/png;base64?
ImageBase64Image Problem Overview
I don't know what we call this. but i found a image at google 404
url("data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAKsAAADVCAMAAAAfHvCaAAAAGFBMVEVYn%2BH%2F%2F%2F%2Bex%2B3U5vd7s%2Bfq8%2Fs0itq72PMLUPvtAAASvklEQVR4AbXBC0JqCQxEwT5Jd7L%2FHc8FdR4g%2BEGtEr8u%2FBHxu7otdzd%2FQPyqlmRp1Pw%2B8aukDfRa1fw28ZtWy4sa89vEb7LCi0zx28RvqgkvouW3id%2FU8pbtWmv5beJXRWNrRmp%2BnfhlHXZm%2BQPi95Vk%2FoD4fZbMHxC%2FryTzB8Tva435A%2BL3rcb8AfH7VjJ%2FQPy%2BHYk%2FIH5facwfEL8iaZcrnKyn%2BAPi57K2VL2WF1hJ%2FAHxQ2tJrg6HteXVjPkD4ge6V3J1%2BF97zhx%2BnXhWb8nacKXlnYPErxNPyfqw4ZYKVuUZdfhd4hmxunY73NICgfWMOvwm8ZQ1pMvlDZdaCic98kjV4beIp8ScpLvsSvhflzqQmqVLB281v0E8pc2bdNne8EayNTPNSbt02PBj4intcKltb%2FNibY%2BLf9aSO%2FyMeMo6XMva3g0vwrWsxvyMeEoc3knZ2g53ZaXa8DzxlHa4J23Jae5aycXTxFPa4WRdXAtdsivckZXG4TniKWtOSlre6y7LG651Wxq5OzxDPGUVIKNwX6ekCv%2B0ddglVPMM8ZQ10FJ4LGVvOEuXRl7OqnmGeEor4Ck%2BtnI1ZEvjDa%2FcPEM8ZQVY4RO9VqUlN%2F84PEM8JQ50cUgXH2mrKlyq5RniOQ4vVjPLHdu86OKGi2eIr%2BgNV6JwljmYO6zlbJsbWp4hPtVrjYpLLV7UHIp7rOVkixtaniE%2BU5I2Nc2FKJytZhTuiac5rLnh4hniEzUbDjXhn3g5W0nNA1aAKm7YPEN8bMecrZYLWl70hkcyBay5YfMM8aHI4aR7xAUVHyirOdhAmRsqniE%2BtOKsRjIXtDzmmRGHVmDFDRfPEB%2BJzMmO01xScdYnVRs6vPHMFG9W4ZrMM8RHouWw43DNhlDWiSVZY3nDoWYc3qzDNZlniPe6w4uoOFjcKhPXuJNWyG6VqjSuhm7%2BiZorUfEM8U5J8nKyMw0tcZLwPxdRtTlUcUgVdGlml0uZ4pqKZ4hr5VUnpSXdUgVa4hA5vHERV1Tp9XhdJTWHksYd%2Ftdarql4hrjQiaPiYLclNSeebVYz5o0W7Ghsa9blmlFtx01rxP8yy5XIPEP8L1W7bjWHlbzhRTwjzXrCK1f3qqSEyBysLVtayKp40yqurcITxJtUgavVHNob%2FinZTWt5VVvWVKvJSttQCkRjb%2FA4vLK5thOeIN6sm9ai5cTFhYRDy%2FyTGpdU0hxkaZvWUrZluTmLims14QniVbywClqgeouT9IZXNWoupGzNqHa3y5LGVYBnipbCSVxcq1meIN54oRXsbEk26S3NmBcZ807K3gon2ZLcxF5tPMVJprlWE54g3nihtbRHm7WjkbxTHSCWwj1r2U4HSMmdQEmWwonNtah4gnhjA9ZSaohmpnpDjWRptDwS25LcQGsc2Bla5sTFtZV4gnixpWmIVWpgRuVwsiV5q7kv0JJcNVIFapydUrHTQKa5IfMEcRKrurSQ0qhsmVR4kea%2B7pIr9NqSrRltWlaxomUgVVyLxBPEYeUGygtszew2KfOBclVpVN2ctCXNidZaaKWmONhc6rKaJwi6xuGkRmWpAkRa7outF9XN%2F7LlmbJmpiCyvBxk%2FtnSqHmGWGk5i2ZcaWBLau5KKHt3Ce%2FsaLMz46VG4cTFm%2FaMOzxFUYWztjzhkNI43JPyYvPAegPxzFRpOYmWF1WywrPUag5xjRapqqxxubijvYFVaC%2Fv7YSDpzxjzlbhpKXxhqcpWshqtECk0Yys6m5utZdD1LCuCifhfyVOapqsxhyiQMmSm58QNdZheZGV5FqwueXiZBUga28DvRte1NQCpQVSUkFqPbIr%2FIxg7arwJqqEg6e5Vuas1Zytyw1ka5uT9ajKI87WbksaLT8mbkXFyWqaa2rOVuFVStUNpGrDoSTPmDfWdlby8kPiHQtoa0vLpXU4WzX%2FS5W2gWxtOHQ24U3CSUmu8BPinR2XVSFyuNAOZ9Fyae1qDu2qcF8suRKeJt7pcW1zaE9xwcVZq7nWtpeTrQ0PrEeq8CTxnsWrlbThELra5ixqbsXWNoeq6nBft6TlOeK9VnG2lfb4TKOOlpOouKPsWg4pb3Nf1uMGusP3iDtKDaTcgMuWvL1FmZOouCtlbwJs1Yb7SuN2Nd8k7mgvXV4OKWALiGkVJ14eyPqQQG9Vc0dWGnn5LnFPTW1z1gW0OdSyag5aHsvaroVs1YZL2dKMt1nzXeKulas52QLanGy3xq4a87Eu2yHZ2uZNWzPjDbDmu8R9a8m7iQNscbKyy%2BWS%2BUzWtqp7qzpA1jPj8KKK7xIPZG2NVWTTSbpKbs5cfEF6y64qV6ctqcKbdvgm8VhSlnWwJbuaV3LzRb11onFt%2BKcVvkl8one7u3bD%2FzJuXnRt%2BFTXVHOWqubQ4rvEEyI1L1Z2h8%2B0eRHLKiBqvkk8IePmxZq1lk%2B0w0nJUHKIlm8ST8ioeVEFtFwbPhA3h8gcdpZV803iCRkVL7Y42bK2w0NlDqXlpJRV803iGZYrnFRxlqwO3eEuN4dSOGlVme8Sz7C37QZqeZPekl0b3nMBreKsp1bNN4lnWIEtF1Vc6i1bVZtwxQX0NC9UrfBN4hk7zaHLNrey1kgVLljATnO2rmj5JvEMqzlrF%2B%2BFXitcsAArnFkdLd8knrFqPmFzyQq0xUm0tJZvEs8oAR0eix0u1ARSqg70NNHyTeIZUqgZ85gdLlgcMjOSRlBqvkk8wwOSp3moJlyoCYfeKkmBVvgm8YyaUJJ5zOJSTXMWSgus%2BC7xjJpA%2BMiquVATXiUcSuGbxDNqmk%2BUxtW82WmurMI3iWd4wifaHo1rNxx2miul8E3iGTXhc4nH0lQ1O80VK3yTeEYNX5SspbEnXFmFbxLPqGm%2BrsvWFFdK4ZvEM2rCt6RmzCWL7xLP2Anfs2M3Fyy%2BSzyjpvmqDoed5YrFd4ln7DRftHI19BRXSuGbxDN6wtdEqjF4lisS3yWeEYUvWlkDNeZKTfgm8ZFu7mqFr%2FKMYae4lFH4JvGBVLgraghf09uQMZdabr5JfKC2q1zV3IgarOLLPMWllptvEo%2B1e7dkq5ZrLkip%2BKqa4lLk5ZvEY15INay9XIqXVGS%2BqsdcirzclYVa7hAPbQFVnJSaC9HCapavqjGXIjXvbNmSxi7eE4%2BsA21OumwuSQUJX1ZjLsVabqR6t7tUlrThhnjEC%2FFy6AKbCy45zdftmEutKm5UcSgHspY7XBEPVAFVHLoCUXPFkr3hi2wutba44QDr5iyeqQ3%2FiAccqOLQDhAV17pG0jZfUuZS5OJaGYiWF%2B2ypOV%2F4q5UQZtDu4G2xK10aeTlC1bhUslciQpYh7PSQtau8ErcVYZ4gXYDcUXLe1lrvBU%2B0VoutFRcWQWo4qwdTlYSr8Q9caDMwc3BDgl3xZpRb%2FORnuVCJHNlla2oOYmLQ8q7Ll6Ie6pgDaQKSCl8IF3WqAgPrbgU2VxpV1kje2EdoOWGlsOJuKMd1g14OdjNp1YjNY%2B0m0s15kYgJVlaFxBVOETuAOK9eEELrDmUli%2Fo8oy94S4Xl2LzQGukEFU46RptQLy3BWWgHSBTvEp32eGRtjTjSriQBKLlShUPrSRcnK2qtIB4Zw3tQNRAbF5FB0vhoS57JFXzZmUtuLiy5gNlTTixlkgB8Y4byhAX0HJ4Y%2FcmWkjz0NrSaMNJ5EiNi3%2FSpPlIayqA3UBcIG5tQTuwBcQOJx3AsrSzxHJ4bKs9U5xoqWnK4U17%2BUzPFLQ4iQ3iRtxQC3gBK5xZJjOutcaSpeYjsUZqKFmGOLxIaflU1jI2ZzuLuLGuLe2yBlrLC1tdWg7ZmWal8KHeGtXG0gLLSdZyha%2BoKYdDl7WIGxpbI7lSicyLqFkH2rVZF%2BwUnymNXNu8WUkVLqSaB6IpIGWXF3Ft1UC6rRq3mhc7TRXgLS2lrKb5VEoz6nCSrtE2V6p4aMeQ8tJaxLU4nGU9o%2BXVTrMF%2BLBgjYqvSNkjL%2BDxhmut5tDb3CF1uwJoEdday6vMTHjVs7GA3g3QU8tXxZJc6Q23yhxWckPCtZW1nLgQ12KFF5Ed3pQ0U7yKp%2Fi6YM%2FI4dZOA3FRRdvhSmaWMxtxI3JzVlP8k9qsVFWdbVvTfENCjcytUoBW46XscE3DizLi1o6KQ4%2FDlZRsWSfBCt%2BSdHGrzGHFOtjFtUgNNJQR78Qjr%2BVwzV4I65SazPJzrQbKq6bl5kapU7bbRryXLo3c3LATYIfMEs3yc1bA44bScqumvJ21jLgrhHdSktNWkONR%2BLmULMnbpQm3pOWkZxHf0R7NKKykDr9iq3ptuexOuJQRZ5lCfE96K5Ct5iNpe118WQKxVeGCxnYDmUL8iUjb2%2BXmexIu9Di9XtgpxJ9wcehuOzwt1gJx4ynEM9K9tS5X7fLempP2dmnDczwjTlLYi%2FiCnHXSe9LWic9k3qvlRTltLU%2Bp2lE1sKUG8bm2DiNpNBpJu5vwwuEdLa%2FWy6p4JL27Dg%2B0pUBsQHxu67C1Vb2dpLlU5h3bG87aS0vNXWtJtip0bbjDhqgB8TkvH1g115qttnfDoW0oNe%2B1Rs0hlqVRc8cSmYP4XBUfUXHNlQ5tqzkpNaXmHVV4lVpq1NxjhYP43JqP2FwracOh7OZQDuXmRmu5sjMO75SWE%2FE5F4%2F09s5wI5abQ0rFoVxZNTes7e7wvy053NpwJj7n4kVCDt29teWypJHFOy0VJ6sN0CrK4dpakmv5pxQeEZ8rQ%2B9alnU2knyo2k64Ix4vh5I5sVNarqW3u8z%2F4mkeEZ8LrCxXtbfWu9t8qqQK0DKHVtEubrWm%2BZ9VPCS%2BJN1828oB4gqwalrFtUjNP3bzkPg7sdXAyhyssF4upWb5Z8c8Jv5QWmpgVRxUsGoulMw%2FPQqPiZ%2Fp8JGVOLQWKAW6%2BCcyF2qGD4gfibe2ead5lXEDpQAu0rv8r2WgtZxl1Twm%2Ftls1HxHK7HDjZV51VIgWmBlSeMKr%2BxseZYXq%2BUx8aY0MxrvVnUC4XNxgYtrJY15taMmNlAztd0lhxfW6MChC1rFY%2BLVjlwzKutVdfhE7xjKXEiX3CuHFzWG0lLycogUXnTtxuaws6DiMfFK09kZQ9K1VSvJ3oRHslIFWuGftdzQUoWzlYONinBILRdaC8TTYPO%2F3nBFnKxLG2um%2BKfXOrg6vBdLrvJSCm9SJpy0RtucrMRq1Zy1woUy0B4HbN60ex0uiEN0KLk1xZXs2paKW9FIqrJrzP%2Fs5k17tJz0GE%2FxohwulGElOUTmTRWl5oI4lKRRsTPhVpIdc6sl10IsFW9WXNpROPH0TkGAVnFpx5a63WSKN5HVXBKwc1btEffsNO8kvBObS5lZTnaUMXFYqbnUltwg75h%2FusMVATXleWW7qk1Xb8KLVfiKlsIlj9Sc1FhFtjITboSTlSp8QMCO5JU11bb1ZlQdIHL4iprmktWROclqGlaWmvsSPiRAIy3lcAhk05vsWgfbU3xFVFyRWTUvSqqa2S7zHEFmRikt7yS18kxxFj6yY67UbNu86U6qIApPEUSasZb7Ek0DqXh5LHa4lDFWc6kd4uUpgsiaKR6pKQ61uHmsZrmyk1ZxpQ1oeYoAzaG4ry1zsuXisVJxpeQdc60N2DxFgGckc1ePixdpHkjVjrnS0kpc6u5SwMtTBKxkybUJN3bUfCaulsMVTVvNP%2BmyNQVe7tjlE%2BJFb1mSLVfV9jaHHS2fiao15sqOd4pL29ArbxXvldV8TPwv6XVV6YXtGTefiiqaMRei2TFXKpzUONxKFWo%2BJt5J0ltlzQxfsCqimSpv86KmrHApBbXA2s2NuKPwMfFQvOELWgvsnEjVQMYtc2UXqjm0xI0yq%2FAx8T0JtyJz8DiekWpjxWoupRqqOamp5VJPsXJt9256wz3iW8oOt1xNaWah3NZJZK7UAg6HLo%2B5tFPgke2SreUe8R1rO9xayTpALFaa2Z3mUhyo4qQ6I67MbLlsyyfFPeI71m7ey0orw2pL256WuFILVHOI41mu1IyK3u0q28094nvCXQHLtqyF9Gq5tA7E4bAViRsrNW%2FCXeK3lDTVVoBI4ZIDVHFYpbTcyIbPiF%2FTSbPT3SUtl6qAuDl4W8UzxC%2Fz6CRciALUcijT4inil%2FV2p4pLtUDcwCol8xTxF8KlKg5VQGtb4jniz7UbWAcox%2BJJ4s%2B5OLiAVnuKJ4m%2FtuawBURbszxL%2FLF4OXgh9s7yNPHHqjisgVLLPE%2F8rXYD7UCrVsXzxN%2Bq4uAGrFj8gPhTXRzKwGprmh8Qf2rlot2AvSp%2BQvyl1nikAlprh58Qf0lqolGBarX8iPhLZWBVqnVsfkb8pTaHcru61PyM%2BEtrDq2UW8sPib%2FUChBvbIcfEn%2FKxWGrpeWnxJ9qVYDyVPgp8bfa2qRmmh8Tf21lq5qfE38uveE3%2FAdr385%2FSVd%2FMAAAAABJRU5ErkJggg%3D%3D") no-repeat scroll 100% 5px transparent
Does anyone know what does this mean ? what ? how? and why they serve image like that ?
Image Solutions
Solution 1 - Image
It's an inlined image (png), encoded in base64. It can make a page faster: the browser doesn't have to query the server for the image data separately, saving a round trip.
(It can also make it slower if abused: these resources are not cached, so the bytes are included in each page load.)
Solution 2 - Image
That data:image/png;base64
URL is cool, I’ve never run into it before. The long string of characters is the base64 encoding of the actual image, i.e. no image call to the server. See RFC 2397 for details.
Side note: I have had trouble getting larger base64 images to render on IE8. I believe IE8 has a 32K limit that can be problematic for larger files. See this other StackOverflow https://stackoverflow.com/questions/3586749/how-to-get-around-ie8-32k-limit-on-datauri-on-base64-encode">thread</a> for details.
Solution 3 - Image
That is, you are referencing an image, but instead of providing an external url, the png image data is in the url itself, embedded in the style sheet. data:image/png;base64 tells the browser that the data is inline, is a png image and is in this case base64 encoded. The encoding is needed because png images can contain bytes that are invalid inside a HTML document (or within the HTTP protocol even).
Solution 4 - Image
They serve the actual image inside CSS so there will be less HTTP requests per page.