"web bug" meaning in English

{
  "forms": [
    {
      "form": "web bugs",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "web bug (plural web bugs)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Internet",
          "orig": "en:Internet",
          "parents": [
            "Computing",
            "Networking",
            "Technology",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Marketing",
          "orig": "en:Marketing",
          "parents": [
            "Business",
            "Economics",
            "Society",
            "Social sciences",
            "All topics",
            "Sciences",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "2002, John R. Levine, Ray Everett-Church, Greg Stebben, Internet Privacy For Dummies, Wiley",
          "text": "When a Web bug is programmed into a Web page, its code looks similar to the code for just about any graphic image appearing on that page.",
          "type": "quotation"
        },
        {
          "ref": "2011, Andrew McStay, The Mood of Information: A Critique of Online Behavioural Advertising, Bloomsbury",
          "text": "Google had a web bug on 92 of the top 100 sites, and on 88 per cent of the total domains reported in the data set of almost 400,000 unique domains.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A small, usually transparent image added by an advertiser to a webpage (to track its popularity) or email message (to track when it is read)."
      ],
      "id": "en-web_bug-en-noun-kAHlkjbO",
      "links": [
        [
          "Internet",
          "Internet"
        ],
        [
          "marketing",
          "marketing#Noun"
        ],
        [
          "transparent",
          "transparent"
        ],
        [
          "image",
          "image"
        ],
        [
          "advertiser",
          "advertiser"
        ],
        [
          "webpage",
          "webpage"
        ],
        [
          "email",
          "email"
        ]
      ],
      "raw_glosses": [
        "(Internet, marketing) A small, usually transparent image added by an advertiser to a webpage (to track its popularity) or email message (to track when it is read)."
      ],
      "synonyms": [
        {
          "word": "tag"
        },
        {
          "word": "tracking bug"
        },
        {
          "word": "tracking pixel"
        },
        {
          "word": "page tag"
        },
        {
          "word": "pixel tag"
        },
        {
          "word": "web beacon"
        },
        {
          "word": "web tag"
        }
      ],
      "tags": [
        "Internet"
      ],
      "topics": [
        "business",
        "marketing"
      ]
    }
  ],
  "word": "web bug"
}

{
  "forms": [
    {
      "form": "web bugs",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "web bug (plural web bugs)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with quotations",
        "en:Internet",
        "en:Marketing"
      ],
      "examples": [
        {
          "ref": "2002, John R. Levine, Ray Everett-Church, Greg Stebben, Internet Privacy For Dummies, Wiley",
          "text": "When a Web bug is programmed into a Web page, its code looks similar to the code for just about any graphic image appearing on that page.",
          "type": "quotation"
        },
        {
          "ref": "2011, Andrew McStay, The Mood of Information: A Critique of Online Behavioural Advertising, Bloomsbury",
          "text": "Google had a web bug on 92 of the top 100 sites, and on 88 per cent of the total domains reported in the data set of almost 400,000 unique domains.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A small, usually transparent image added by an advertiser to a webpage (to track its popularity) or email message (to track when it is read)."
      ],
      "links": [
        [
          "Internet",
          "Internet"
        ],
        [
          "marketing",
          "marketing#Noun"
        ],
        [
          "transparent",
          "transparent"
        ],
        [
          "image",
          "image"
        ],
        [
          "advertiser",
          "advertiser"
        ],
        [
          "webpage",
          "webpage"
        ],
        [
          "email",
          "email"
        ]
      ],
      "raw_glosses": [
        "(Internet, marketing) A small, usually transparent image added by an advertiser to a webpage (to track its popularity) or email message (to track when it is read)."
      ],
      "synonyms": [
        {
          "word": "tag"
        },
        {
          "word": "tracking bug"
        },
        {
          "word": "tracking pixel"
        },
        {
          "word": "page tag"
        },
        {
          "word": "pixel tag"
        },
        {
          "word": "web beacon"
        },
        {
          "word": "web tag"
        }
      ],
      "tags": [
        "Internet"
      ],
      "topics": [
        "business",
        "marketing"
      ]
    }
  ],
  "word": "web bug"
}