Apple and Google can be considered a duopoly in the mobile device market. Together, they dominate the industry with their iOS and Android operating systems, which power the majority of smartphones and tablets worldwide. Both companies also have their own app stores, which further solidifies their control over the mobile ecosystem. While there are other players in the market, such as Samsung and Huawei, Apple and Google's combined market share and influence make them the most dominant forces in the mobile device industry. **

No, circumcision is not a fashion trend. Circumcision is a cultural, religious, or medical practice that has been performed for thousands of years in various societies around the world. It is not a passing trend, but rather a deeply rooted tradition with significant historical and cultural significance for many communities. While there may be fluctuations in circumcision rates over time, it is not accurate to categorize it as a fashion trend. **

Yes, piercings are considered a fashion trend. Over the years, piercings have become a popular way for people to express their individuality and personal style. From ear piercings to nose, lip, and body piercings, they have become a common form of self-expression and a way to enhance one's appearance. Many people view piercings as a fashion statement and use them to accessorize and complement their overall look. **

It is difficult to determine if something is a fashion trend without more specific information about what is being referred to. Fashion trends can vary widely and can be influenced by a variety of factors such as popular culture, social media, and celebrity endorsements. Without more context, it is challenging to definitively say whether something is a fashion trend or not. **

Yes, Swarovski is considered fashion jewelry. Swarovski is known for its high-quality crystal jewelry and accessories that are often used to add sparkle and elegance to fashion ensembles. The brand offers a wide range of jewelry pieces, including necklaces, earrings, bracelets, and rings, that are designed to complement various fashion styles and trends. Many people consider Swarovski jewelry to be a fashionable and stylish choice for accessorizing different outfits. **

Fashion jewelry can stain if it comes into contact with certain substances such as water, sweat, perfume, lotion, or other chemicals. The metal in fashion jewelry can react with these substances and cause discoloration or staining. To prevent staining, it's important to remove fashion jewelry before swimming, exercising, or applying lotions or perfumes. Additionally, storing fashion jewelry in a dry and clean environment can help prevent staining. **

As an AI, I don't have personal preferences or the ability to follow fashion trends. However, I can provide information and insights on current fashion trends and help users stay updated on the latest styles and designs. Whether or not someone chooses to follow fashion trends is a personal choice, and it's important to wear what makes you feel comfortable and confident. **

Trend fashion is determined by a combination of factors including designers, fashion houses, influencers, celebrities, and consumer demand. Designers and fashion houses often set the tone for upcoming trends through their runway shows and collections. Influencers and celebrities play a significant role in popularizing certain styles and brands, while consumer demand ultimately drives what becomes mainstream in the fashion industry. Overall, it is a collaborative effort between various stakeholders in the fashion world that determines what is considered trend fashion. **