There are also cookies that remember more detailed information about you. Perhaps your interests, your web browsing patterns, etc. This means that a site can provide you more targeted content – often in the form of ads. There are types of cookies, called <em>third-party</em> cookies, that come from sites you’re not even visiting at the time and can track you from site to site to gather information about you, which is sometimes sold to other companies. Sometimes you can block these kinds of cookies, though not all browsers allow you to.

Mae yna hefyd gwcis sy'n cofio gwybodaeth fwy manwl amdanoch chi. Efallai eich diddordebau, eich patrymau pori ar y we, ac ati. Mae hyn yn golygu y gall gwefan roi mwy o gynnwys wedi'i dargedu i chi - yn aml ar ffurf hysbysebion. Mae yna fathau o gwcis, o'r enw <em>cwcis trydydd parti</em>, sy'n dod o wefannau nad ydych chi hyd yn oed yn ymweld â nhw ar y pryd a gallan nhw eich olrhain o wefan i wefan i gasglu gwybodaeth amdanoch chi, sydd weithiau'n cael ei gwerthu i gwmnïau eraill. Weithiau gallwch rwystro'r mathau hyn o gwcis, er nad yw pob porwr yn caniatáu i chi wneud hynny.